Scouting For Girls, Official Handbook of the Girl Scouts

by Girl Scouts of the United States of America

SECTION XV

NATURE STUDY FOR GIRL SCOUTS

FOREWORD

The following section was specially prepared for the Girl Scouts by Mr. George H. Sherwood, Curator, and Dr. G. Clyde Fisher, Associate Curator, of the Department of Public Education of the American Museum of Natural History. All the illustrations used were supplied by the Museum, and the tests in the various subjects were devised by the same authors.

The American Museum of Natural History in New York conducts special courses of lectures in all of the branches of Natural History, and extends a cordial invitation to all Girl Scouts to visit the Department of Education if wishing help in preparation for their Nature Study tests.

Contents

1. Introduction to Nature Study.

2. Plants: Flowers and Ferns and Trees.

3. Animals: Mammals

Birds

Reptiles

Amphibians

Fishes

Invertebrates

4. Geology.

AN EGRET "ROOKERY" IN SOUTH CAROLINA.
The demand for the nuptial plumes of this bird in the millinery trade brought it to the verge of extermination. Range: Temperate and tropical America. Habitat Group in The American Museum of Natural History.

1. Introduction to Nature Study

To the solid ground
Of Nature trusts the mind which builds for aye.

—Wordsworth.

To understand nature is to gain one of the greatest resources of life.

—John Burroughs.

Nature Study means getting acquainted with the multitude of creatures, great and small, which inhabit the land, the water, and the air, and with the objects which surround them. Mother Nature has many, many secrets which she will reveal to sharp eyes and alert minds. It is, of course, impossible for any one to learn all these secrets, but the mastering of a few makes it easier to learn others, until finally it becomes clear that all life is related and that the humblest creature may be of the greatest importance to the welfare of the highest.

It is for these reasons that the Girl Scout should learn as much as possible of the Wonders of Nature. This study may begin wherever you are, but rapid progress will be made by rambles afield and by visits to the great Natural History Museums. For example, a visit to the exhibition halls of the American Museum of Natural History in New York will answer many of your questions about animals you have seen and will enable you to answer many others for yourself, when you go out into the country.

Nature Study in its broadest application includes all of the natural sciences, such as zoology, botany, geology, meteorology, and astronomy. So, there are many fascinating fields for study and enjoyment, and it does not matter much where we begin, whether it be Wild Flowers, Trees, Birds, Butterflies, or Stars.

THE BULLFROG IN ITS NATURAL SURROUNDINGS
See Snake, Turtle and Dragonfly and notice the tongue of the frog. Habitat Group in Museum of Natural History

Of the more practical subjects especially suited to the activities of the Girl Scout are those civic problems which can only be solved by team-play; that is, by working together. Among these may be mentioned: The preservation of birds, wild flowers, and forests; control of mosquitoes, house-flies, rats, weeds; diseases of plants and animals, including man.

The civic nature of these problems is appreciated when we realize that it would do little good, for example, for one person to destroy the breeding-places of mosquitoes on his premises, if his neighbors did not do likewise about their homes; or for one orchardist to cut out the blight from his pear-trees or the black-knot from his plum-trees, if his neighbors did not co-operate with him by ridding their orchards of these diseases.

These practical questions are so well presented, together with plans for their solution, in Civic Biology, by Clifton F. Hodge and Jean Dawson (Ginn & Co.), that instead of going into details here, both the Girl Scouts and their Leaders are referred to this most useful work.

All objects of Nature are either living (organic) or non-living (inorganic). The non-living bodies include the minerals and rocks. The living bodies are either plants or animals. Plants may be divided into two great groups, the flowerless plants and flowering plants. In general the flowerless plants reproduce by means of spores, like the mushroom and the ferns, while the flowering plants reproduce by means of seeds.

ROCKY MOUNTAIN GOAT
This animal is really not a goat, but is more nearly related to the antelopes. Range: The higher mountains from Alaska south to California. Group in American Museum of Natural History.

Animals may be separated into two great groups, those without backbones (invertebrates) like an oyster, a cricket, or an earthworm, and those with backbones, e.g., a dog, a fish. In this brief study we shall not go into much detail about invertebrates, but with the backboned animals or vertebrates we shall go a little further. These may be divided into five general groups: (1) Fishes; (2) Amphibians, which include frogs, toads, and salamanders; (3) Reptiles, which include alligators, crocodiles, turtles, lizards, and snakes; (4) Birds; (5) Mammals.

This simple analysis may be clearly shown by the following diagram:

								Mammals
						Vertebrates		Birds
								Reptiles
				Animals				Amphibians
								Fishes
		Living Bodies				Invertebrates
		(Organic)				Flowering Plants
Objects						Flowerless Plants
of
Nature		Non-living Bodies
		(Inorganic)

This classification could be carried further at every point, but this will be far enough for present purposes. It should be remembered in any classification that there are no hard and fast lines in Nature. For example, some creatures are on the border-land between plants and animals, and again some animals are between the backboned animals and those without backbones.

GREAT-LEAVED MAGNOLIA
A forest tree with large solitary white flowers. Range: Southern and Southeastern United States.

2. Plants
Wild Flowers and Ferns

Flower in the crannied wall,
I pluck you out of the crannies;
Hold you here, root and all, in my hand.
Little flower—but if I could understand
What you are, root and all, and all in all,
I should know what God and man is.

—Tennyson.

Do you know the earliest spring flower in your neighborhood? In the northern United States it is usually found in bloom before all the snow of winter is gone. In some swamp or along some stream where the snow has melted away in patches it is possible to find the Skunk Cabbage in bloom very early in the spring. See how early you can find it. In the southern United States, one of the earliest spring flowers is the yellow Jessamine, which twines over bushes and trees thus displaying its fragrant, golden bells.

TRAILING ARBUTUS
One of our earliest spring flowers, usually growing in patches in sandy or rocky woods. Range: Eastern United States westward to Michigan. Photograph by G. Clyde Fisher.

As the season advances, other flowers appear, and we find the Spring Beauty, the Trailing Arbutus, the Bloodroot, and the Hepatica. What delightful associations each of these names brings to our minds! By the time summer is here we have an entirely different flower-population in the fields and woods—the Cardinal Flower with its intense red color and the Pink Lady's-Slipper with its drooping moccasin-shaped lip are to be found then. In the autumn we have a different group of flowers still—the Goldenrods, the Asters, and the Fringed Gentian, the season closing with our latest fall flower, the Witch-hazel.

PINK MOCCASIN-FLOWER

Some flowers and ferns grow best in the shady woods, others in the sunny fields, some on the rocks and others in the marshes. We soon learn where to look for our favorites. In taking tramps along the roads, across the fields, through the woods, and into the swamps, we could notice along the roadside Bouncing-Bet, Common Yarrow, Dandelion, Thistles, and Goldenrod; in the fields and meadows, we would see the Ox-eye Daisy, Black-eyed Susan, Wild Carrot, and the most beautiful fall flower of the northeastern United States, the Fringed Gentian; in the woods, Mountain Laurel, Pink Azalea, a number of wild Orchids, Maidenhair Fern, and Jack-in-the Pulpit; in the marshes, Pink Rose-mallow, which reminds us of the Hollyhocks of our Grandmother's garden, Pickerel-weed, Water-lily, and Marsh Marigold.

It is natural to want to know the name of any plant that interests us, and this is important. As in the subjects of Birds, there are many helpful books on Flowers and Ferns. Beginners will find "The Flower Guide," by Chester A. Reed (Doubleday, Page & Co.) to be useful. After a good start has been made, such books as Gray's Manual, or Britton and Brown's Illustrated Flora should be used.

Our pursuit, however, should not stop with the name of a plant. That is a mere beginning. Even slight attention will uncover many fascinating things in the lives of plants. Why cannot a farmer raise a good crop of clover-seed without the bumble-bees? What devices are there among the Orchids to bring about cross-pollination? (See "Our Native Orchids," by William Hamilton Gibson). Examine the flower of the wild Blue Flag, and see whether you can determine how the bumble-bee cross-pollinates this plant. Do the Hummingbirds cross-pollinate some flowers? In what plants is the pollen scattered by the wind? Do these plants produce nectar?

GAILLARDIA OR BLANKET-FLOWER
Daisy family. Range: Hills and plains of western United States and Canada. Photograph by Albert E. Butler.

How do the various plants scatter their seeds? How are the Hickory-nuts and Walnuts scattered? The Dandelion's and Thistle's seeds have flying-hairs or parachutes and are blown about by the wind. What other plants can you find whose seeds are scattered in the same way? Can you discover a plant whose seeds are carried by water? The Witch-hazel shoots its seeds. What other plants can you find that have explosive fruits? Cherry-seeds are carried by birds. Mention some other seeds that are carried in this way. It would take very little observation to learn how Burdock-burs, Cockle-burs, Stick-tights, Beggar-lice, Spanish-needles, and such hooked fruits are scattered.

BLACK-EYED SUSAN
A beautiful and abundant flower of the fields. Range: Eastern North America westward to the Rocky Mountains. Photograph by G. Clyde Fisher.

Learn the names of the principal noxious weeds of the farm and garden, and also learn the best methods of combating them.

Learn to know the plants in your vicinity which are used in the making of drugs.

LOCO-WEED
A poisonous plant which produces loco-disease in cattle, sheep, and horses that eat it. Range: Plains from Montana to Colorado. Photograph by Albert E. Butler.

Learn to know the poisonous plants around your home and summer camp. Are the following to be found there: Poison Ivy, Poison Sumach, Loco-weed, Bittersweet (Salanum Dulcamara), Black Nightshade, Jimsonweed, Poke-weed, Poison Hemlock?

SHOWY PRIMROSE
Not a true Primrose, but a member of the Evening Primrose Family. Range: Prairies of western United States and northern Mexico; also naturalized farther east. Photograph by Mr. and Mrs. Leo E. Miller.

Trees

He who wanders widest lifts
No more of beauty's jealous veils,
Than he who from his doorway sees
The miracle of flowers and trees.

—Whittier.

The trees of the forest are of two classes, deciduous trees and evergreen trees. To the former belong those which shed their leaves in the fall, are bare in the winter, and then grow a new crop of leaves in the spring, e.g., oaks, elms, maples. The evergreen trees shed their leaves also, but not all at one time. In fact, they always have a goodly number of leaves, and are consequently green all the year round, e.g., pines, spruces, firs.

RHODODENDRON OR GREAT LAUREL
A tall shrub, or sometimes a tree, growing in woods and along streams. Range: Eastern North America from Nova Scotia to Georgia. Photograph by Albert E. Butler.

The uses of wood are so many and various that we can only begin to mention them. In looking about us we see wood used in building houses, in making furniture, for railroad ties, and for shoring timbers in mines. In many country districts wood is used for fuel. And do you realize that only a short time ago the newspaper which you read this morning and the book which you now hold in your hand were parts of growing trees in the forest? Paper is made of wood-pulp, mostly from Spruce.

CHRISTMAS FERN
An evergreen fern growing in woods and rocky places. Range: Eastern United States and Canada. Photograph by Mary C. Dickerson.

Besides the direct uses of wood, we turn to the forest for many interesting and valuable products, varying in importance from a balsam-pillow filled with the fragrant leaves or needles of the Balsam Fir, to turpentine and rosin (naval stores), produced chiefly by the Long-leaved Pine of the Southeastern States. Spruce gum is obtained from the Black Spruce and Red Spruce. Canada balsam used in cementing lenses together in microscopes, telescopes, and the like, comes from the Balsam Fir. Bark for tanning comes from Oak and Hemlock. The Indians of the Eastern Woodlands or Great Lakes area made canoes and many other useful articles of the bark of the Canoe or Paper Birch. Baskets are made from Willow twigs. Maple sugar comes chiefly from the Sugar Maple.

IN A TURPENTINE GROVE
The long-leaved Pine furnishes most of the turpentine and rosin of commerce. Range: Virginia to Florida and Texas. Photograph by G. Clyde Fisher.

BLACK SUGAR MAPLE
The sap of this tree, as well as the more common Sugar Maple, is the source of maple sugar. Range: Eastern United States and southeastern Canada.

The turpentine industry is the chief one in parts of the South where the Long-leaved Pine thrives. The United States produces more turpentine and rosin than any other country in the world. The turpentine is used in paints and in various arts. The rosin is used in varnish, laundry soap, etc. These two products come from the sap or "gum" of the pine tree. The sap is secured by tapping or "boxing" the tree, and then keeping the cut ducts of the sap-wood open by "chipping" or "pulling," that is, by putting a new "streak" on the tree. This has to be done once a week from March 1 to November 1. The sap used to be collected in a "box" or deep notch cut in the base of the tree, but the modern method is to have it run into cups made of zinc or of burned clay similar to flower-pots. The sap is taken to a turpentine still where it is heated over a furnace. This drives off the turpentine or "spirits" as steam or vapor, which is condensed to liquid again by passing through the worm of the still surrounded by cold water. The rosin or resin is left behind.

COMMON FALL MUSHROOM
An excellent article of food growing commonly in old pasture fields. Range: Temperate and tropical regions all over the world. Photograph by G. Clyde Fisher.

The Sugar Maple grows from Florida and Texas northward to Manitoba and Quebec, but it is only in the northern part of its range that the maple sugar industry thrives. This delicious food is one of the many that we learned to utilize from the Indians. The sap is obtained by tapping the tree in the spring before the leaves come out, the best weather for the flow of sap being that when it freezes at night and thaws in the daytime. The sap is boiled down; that is, the water is driven off and the sugar remains. It takes about three gallons, or a little more, of sap to make a pound of maple sugar. Three to four pounds of sugar is an average yield for one tree in a season. Much of the sap, however, is not boiled down into sugar, but the boiling is stopped while it is in the form of syrup. If you have ever eaten buckwheat cakes with real maple syrup you will always esteem the Sugar Maple tree.

The forests perform extremely valuable services for mankind entirely apart from the products they yield.

First, they prevent erosion, or the washing away of soil by the water that falls as rain. After the trees have been cut away, very often, especially upon hillsides, the most productive soil is washed away, usually clear off of the original owner's farm, and deposited in the flood-plains or bottoms of creeks and rivers or in river deltas—in places where it cannot be utilized to any great extent. Thus erosion causes a tremendous loss to farmers, and it is chiefly due to the thoughtlessness of the American people in destroying the forests.

Second, and chiefly related to this, is the fact that the floods upon our rivers, which every year take such heavy toll in property and in human life, are due to the cutting away of the forests. This allows the water from rain and melting snow to reach the streams at times faster than it can be carried off, and so we have a flood. The forest floor, with its undergrowth and humus, in those localities where the forests still exist about the headwaters of our rivers, acts like a huge layer of blotting paper which holds the water back and allows it to escape to the streams slowly, and so floods are avoided.

Third, and related to the above, is the fact that the water supply of our cities would be more constant if the forests had not been cut away. In these cases the summer droughts make much greater the danger from water-borne diseases.

WESTERN YELLOW PINE A magnificent tree which furnishes valuable timber. Range: Hills and mountains of western United States. Photograph by Albert E. Butler.

ROADS THROUGH THE ASPENS
Range: Northern United States and Canada, south in the Rocky Mountains to Mexico. Photograph by Albert E. Butler.

It is only in recent years that the American people have begun to realize the necessity of the conservation of our forests, and in many sections much has been done to redeem the criminal thoughtlessness in destroying our forests and to restore those devastated by forest fires. Reforestation operations have accomplished a great deal, and the organization to prevent forest fires emphasizes the old adage that "an ounce of prevention is worth a pound of cure." Also the people are being taught correct forestry practices, such as cutting only ripe trees and allowing the rest to grow, instead of clearing the land entirely, as was formerly done so universally.

BALD CYPRESS DRAPED WITH SPANISH "MOSS."
This tree is almost entirely hidden by this "moss," which is really a flowering plant of the Pineapple family. Range: In swamps and along rivers from Delaware to Florida, west to Texas, north to Missouri and southern Indiana. Photograph by G. Clyde Fisher.

The life history of every tree is interesting; how it breathes by means of its leaves, just as the animals do by means of gills or lungs; how it manufactures starch by means of the green matter in the leaves; how the starch is changed to sugar and other substances which are carried to other parts of the tree in the sap; how the sap flows upward in the vessels in the sap-wood and downward in the vessels of the inner bark; how the entire heart-wood of a tree is dead and the only living part is the sap-wood and the innermost bark.

One of the first things we shall want to know when we get out into the woods is the name of the tree that interests us. For this purpose the books given as references under "Trees" will be useful.

TIMBER WOLVES ON THE TRAIL
Closely related to foxes and dogs. Range: Formerly over most of North America. Habitat Group in American Museum of Natural History.

BABY OPOSSUMS RIDING ON THEIR MOTHER'S BACK
For the first few weeks after they are born the mother carries her babies in her pocket; later they ride on her back holding on by clinging to her fur with their paws and by wrapping their tails about that of their mother. Range: Middle and Southern States. From Group in American Museum of Natural History.

3. ANIMALS
Mammals

Mammals differ from birds in that they have hair instead of feathers, and that they are first fed upon milk produced by the mother. Unfortunately the mammals are usually called simply animals, but the latter is obviously too inclusive a term and should not be used in this way. There is no reason why the name mammal should not be commonly used, just as birds, reptiles, amphibians, and fishes are used for the other groups of backboned animals.

NEW YORK WEASEL IN SUMMER PELAGE

OTTER WITH ITS FAVORITE FOOD
The Otter belongs to the Weasel family, and feeds almost entirely upon fish. Range: This and related varieties over Northern and Eastern North America. From Group in American Museum of Natural History.

In the United States the lowest or most primitive mammal is the Opossum. The baby Opossums—from six to a dozen of them—are born when very small and undeveloped and are immediately placed by the mother in an external pouch, where they continue to grow until they are too large to get into their mother's pocket; then they frequently ride upon their mother's back, clinging to her fur with their finger-like toes and wrapping their tails about their mother's tail. The Opossum is the only animal in this country the young of which are carried around in the mother's pocket, and the only one which has a prehensile tail; that is, one used for coiling around and clinging to branches, and the like. Its food is various, consisting of both animal and plant material—insects, young birds, pawpaws, persimmons, etc. In the food devoured the Opossum probably does more good than harm.

NEW YORK WEASEL IN WINTER
A blood-thirsty cousin of the Otter and the Mink. Range: This and related species found all over United States and Canada. Group in American Museum of Natural History.

In their food habits many mammals are decidedly injurious. Rats, Weasels, Minks, and Foxes destroy poultry; Wolves and Pumas kill domestic and game animals; Woodchucks or Groundhogs eat clover and various garden plants; Moles damage the lawns; Rats, Mice, and Gophers spoil and devour grain; Mice and Rabbits girdle fruit trees, thus killing them.

RACCOON AT ENTRANCE TO ITS DEN IN A HOLLOW TREE
A near relative of the bears. Note the black face-mark and the ringed tail. Range: This or a related variety occurs in all parts of United States. Photograph from American Museum of Natural History.

On the other hand, many mammals furnish food; e. g., Rabbits, Elk, and Deer. This was more important in pioneer times than at present. Many furnish furs used as articles of clothing; e. g., Raccoon, Fox, Muskrat, Mink, Otter, Marten, Mole, New York Weasel and other northern weasels in their winter coats.

POLAR BEAR
An expert swimmer. Feeds upon seals, fish and other animal food. Range: Arctic regions of the world. Habitat Group in American Museum of Natural History.

Many furs are usually sold under trade names that are entirely different from the true name of the animal. A list of a few fur-bearing mammals of the United States having trade names differing from the true names follows:

The True Fur	The Trade Name
Dark blended Muskrat	Russian Otter
Mink blended Muskrat	Natural River Mink
Natural Muskrat[6]	River Mink
Natural Jersey Muskrat	River Sable
Plucked and Seal-dyed Muskrat	Hudson Seal
Plucked and Seal-dyed Muskrat	Aleutian Seal
Skunk	Black Marten
Striped Skunk	Civet Cat
N.Y. Weasel in winter pelage	Ermine

SKUNKS—MOTHER AND YOUNG HUNTING FOR GRASSHOPPERS AND CRICKETS
Noted for its ability to emit a most unpleasant odor when disturbed. Range: Eastern North America. Portion of Group in American Museum of Natural History.

MINK
A cousin of the Weasel and Otter, the Mink feeds upon frogs, crayfish, mice, bird's eggs, etc. Range: This and closely related forms over most of United States, Canada, and Alaska. From Group in American Museum of Natural History.

A few suggestions for observation or study:

1. What peculiar instinct or habit has the Opossum developed?

2. How does the flight of a Bat differ from that of a Flying Squirrel?

3. Can you notice any peculiarity in the Rabbit's track?

4. Mention three mammals that hibernate.

5. Describe the methods of defense in the following mammals: Armadillo, Porcupine, Skunk.

6. Why do the front teeth of the Squirrel and the Beaver continue to grow?

The best way to find the answers to these questions is by actual observation of the animals, but when this is impossible, the references given under "Mammals" will be found useful.

RED FOX RETURNING TO ITS YOUNG FROM SOME FARMER'S HEN-ROOST
The Cross Fox, the Silver Fox, and the Black Fox are color phases of the Red Fox, and not different species. Range: Northern North America south to Georgia. Habitat Group in American Museum of Natural History.

BALD-EAGLE
The American Eagle, the Emblem of our Country. Range: United States

Birds

He who takes the first step in ornithology is ticketed for the whole trip.—John Burroughs.

A GREBE COLONY IN SASKATCHEWAN
Showing the Western Grebe and the smaller Grebe. Note the young Grebe riding on its mothers' back. Another parent is covering its eggs preparatory to leaving the nest. Range of both these species: Western North America. Habitat Group in the American Museum of Natural History.

The love of the beautiful seems to be innate; that is, born in us. And the birds appeal to this in at least two ways: First, on account of the beauty of their songs, and second, on account of the beauty of their plumage.

SCREECH OWL
The Screech Owl feeds largely upon mice and other destructive rodents. Range: Eastern North America.

Among the birds that have especially beautiful songs are the Thrushes, which include the Robin and the Bluebird, the finest singer in this family probably being the Hermit Thrush. In the Southern States there is no more popular singer among the birds than the Mockingbird. But it should be remembered that a bird's song cannot be separated from the associations which it calls up in one's memory. So that the performance of an ordinary songster may be more pleasing to one than that of some finer one because of youthful associations.

SAND HILL CRANES IN FLORIDA
Unlike the Herons, these birds fly with neck fully extended. Their loud, resonant trumpeting is as characteristic as the honking of Wild Geese. Range: North America. Habitat Group in The American Museum of Natural History.

GREAT HORNED OWL
Rabbits constitute a favorite food when available. Poultry and other birds are also destroyed by this owl. Range: Eastern North America.

It seems to be a general law of nature that the finest songsters have the plainest coats.

BROWN PELICANS IN FLORIDA
The Pelicans nest in colonies, and the young feed from the parents' throats. Range: Gulf coast of U. S. and southward. Habitat Group in The American Museum of Natural History.

EGRETS: PARENT BIRDS

Among the birds that we enjoy on account of their beautiful plumage are the Egrets, every feather of their coats being as white as snow, and the plumes of these birds are so beautiful, and human beings have been so thoughtless that the Egrets have been almost exterminated in order to supply the millinery trade. These plumes, known as aigrettes, grow on the backs between the shoulders of both the male and female birds, and are worn only during the nesting season. The only time during the nesting season that the plume hunter finds it profitable to hunt these birds is when the young are in the nest. At any other time the birds would be so wild that the plume hunter could not easily shoot them. When the young are in the nest the parental love is so strong that the adult birds cannot resist the instinct to return to feed the nestlings when they are begging for food. In this way both the father bird and the mother bird become an easy prey for the ambushed plume hunter, and there is but one thing that can happen to the baby Egrets in the nest after both of their parents have been killed—they starve to death. This is one of the most cruel phases of the plume trade, and there is no other way to secure the aigrette plumes of the Egrets than by killing the adult birds. Fortunately, in the United States it is against the law to shoot these birds, and it is against the law to import the plumes. Until recently it has not been illegal to wear these plumes, and the fact that there are still a few women who adorn their hats with them has encouraged the illegal and cruel killing of these birds in our country, or the smuggling in of the plumes from some other country. In the latter part of 1919 the federal regulations have been interpreted to make it illegal to possess aigrette plumes, and henceforth the law will be so enforced. This is the successful culmination of a long fight by the Audubon Society.

GOLDEN PLOVER
The Golden Plover makes the longest single flight known to be made by any bird in migration,—that is, 2,500 miles from Nova Scotia across the open ocean to South America. Range: North and South America.

BOBOLINK
During the autumn migration this bird is the Reedbird or Ricebird. Range: North and South America.

A few other birds of striking plumage are the Bluejay, the Bluebird, the Baltimore Oriole, the Scarlet Tanager, the Cedar Waxwing, and Red-winged Blackbird.

Turning from the esthetic value of birds, which depends, among other things, upon the beauty of their songs and the beauty of other plumage, we may consider the value of birds in dollars and cents.

WILD TURKEY IN WEST VIRGINIA Our most magnificent game-bird. Note how much the young resembles the dead leaves. Range: Eastern United States west to Nebraska and Texas. Habitat Group in The American Museum of Natural History.

NORTHERN SHRIKE IMPALING A HOUSE SPARROW UPON
A THORN The habit illustrated here has given the Shrike the name of Butcher-bird. It is surprising to find a song-bird with the habits of a bird of prey. Range: Northern North America.

DUCK HAWKS ON THE PALISADES OF THE HUDSON The "Noble Peregrine" of falconry carrying a pigeon to its young. Range: North and South America. Habitat Group in The American Museum of Natural History.

Every farmer and gardener must cultivate his crops and fight the weeds which are always crowding out the plants he is trying to raise, and in this fight he is helped by a great many birds of various kinds. Among these are the Mourning Dove, the Bob-White, and members of the Sparrow family, such as the Goldfinch, the Junco, and the Song Sparrow. In this country, in the aggregate, these seed-eating birds destroy every year tons of seeds of the noxious weeds, and are therefore valuable friends of the gardener and farmer. For more definite data see bulletins published by the U. S. Department of Agriculture, or "Useful Birds and Their Protection," by Edward Howe Forbush (Massachusetts Board of Agriculture).

A KILLDEER FAMILY
This plover is common in meadows, cultivated fields, and about ponds and lakes. It gets its name from its note. Range: North and South America.

Thousands of bushels of grain are eaten or spoiled by small mammals, such as mice, rats, and spermophiles or gophers. To the relief of the farmer, many birds feed upon these destructive little rodents. The Crow occasionally captures a mouse, while the Shrikes or Butcher-birds catch a great many. The Screech Owl feeds largely upon mice. The Red-tailed Hawk is called the Hen-hawk or Chicken-hawk by most farmers, but this is very unfair to the bird, for its principal food is mice. In fact, most of the Hawks and Owls of the United States are really valuable friends of the farmer because of the injurious rodents which they devour. (See "Hawks and Owls of the United States," by A. K. Fisher.)

STARLING
Introduced 1890 into New York City; since spread over northeastern states. Western and central Europe, New England and Middle Atlantic States.

To be fair, it must be admitted that there are a few exceptions; that is, that there are a few Hawks and Owls which do more harm than good. The Sharp-shinned Hawk kills many harmless songbirds and occasionally young game birds and young chickens. The Cooper's Hawk, which nests throughout the United States, is a real chicken hawk, and the worst one in the country. The Duck Hawk, the "Noble Peregrine" of falconry, in this country feeds largely upon domestic pigeons, but no bird student would wish to see it exterminated on account of this habit.

There are a number of birds which are valuable friends to all the people because they are scavengers. The Herring Gull, which is the commonest gull of the harbors of the United States, and which is also found on inland lakes and rivers, by feeding upon all kinds of refuse animal and plant materials makes the waters about our cities more healthful. This is especially true of the coast cities which dump their garbage into the waters not far distant. The Turkey Vulture, the Black Vulture or Carrion-Crow, and the California Condor make the fields and woods of the country more healthful by devouring the carcasses of animals, and the first two species eat the offal from slaughter houses and even scraps of meat from the markets in some of our Southern cities.

COMMON TERN
A close relative of the gulls. Range: Northern Hemisphere, northern South America and Africa.

GREAT BLUE HERON
Frequently miscalled Blue "Crane." The long legs indicate that this is a wading bird. Range: Western Hemisphere.

The most valuable group of birds from the standpoint of the farmers, the orchardists, and the gardeners is the insect-eating birds. Among these are the Wood Pewee, the Phoebe, the Kingbird, and all of the Flycatchers; the Purple Martin and all of the Swallows; the Nighthawk and Whip-poor-will. The Yellow-billed and Black-billed Cuckoos and the Baltimore Oriole feed largely upon tent caterpillars and others caterpillars which defoliate the fruit and shade trees. The Sparrow Hawk has been wrongly named, for it eats a thousand times as many grasshoppers as it does sparrows. The Chickadees, Brown Creepers, and many of the Warblers feed largely upon insects and insect eggs which they glean chiefly from the trees. The Rose-breasted Grosbeak and the Bob-White eat the Colorado potato-beetle. In the West the Franklin's Gull follows the farmer in the fields and picks up great numbers of destructive insects.

In learning the value of our feathered friends it is necessary to learn to know the birds, and in this quest great help can be obtained from books. Beginners will find the following useful:

"Land Birds East of the Rockies," by Chester A. Reed.

"Water and Game Birds," by Chester A. Reed.

"Western Bird Guide," by Chester A. Reed. (All published by Doubleday, Page & Co.)

For more advanced students the following are recommended:

"Handbook of Birds of Eastern North America," by Frank M. Chapman (D. Appleton & Co.).

"Handbook of Birds of Eastern North America," by Florence Merriam Bailey (Houghton, Mifflin & Co.).

Our study of birds should not stop with the name, because we shall find many things of interest in the home life of birds, many things that seem to reflect our own lives. (See "Home Life of Wild Birds," by F. H. Herrick. G. P. Putnam's Sons.)

If we like to hear birds sing, if we enjoy the beauty of their coats, and if they are valuable neighbors from the standpoint of dollars and cents, then it is worth while to consider how we may have more of them about our homes. Every girl can do a great deal to attract birds.

First, by putting up nesting boxes. Since the people of our country have destroyed so much of our native forests and undergrowth, have drained so many of our swamps, and have cultivated so much of the grassy prairie, many birds have difficulty in finding suitable places to nest. This can be remedied in the case of birds that nest in cavities, such as the House Wren, Tree Swallow, Purple Martin, Screech Owl, Chickadee, and Bluebird, by putting up nesting boxes. For those that nest in shrubbery, like the Catbird and the Brown Thrasher, shrubs and vines may be planted so that the desirable tangle may be had.

A MOTHER MALLARD AND HER FAMILY
The Wild Mallard is the original of many of the domesticated ducks. Range: Northern Hemisphere.

Second, by putting out bird baths. In this improved country of ours, there are doubtless large areas in which wild birds have difficulty in finding suitable places to bathe. Artificial bird baths are more attractive to birds in the summer time than during cold weather, but they will be used even in winter if kept free from ice. Do not place a bird bath so close to a shrub, tree, or building that a house cat may stalk the birds from behind it. The house cat is probably the worst enemy of our native songbirds.

Third, by establishing feeding stations, especially in winter when snow covers the natural food of so many birds. When birds have enough to eat they rarely suffer severely from the cold.

Fourth, by cooperating with the authorities in seeing that the laws protecting the birds are enforced.

The Audubon Society has done much effective work along these lines, and a Girl Scout should join this society, whose headquarters are 1974 Broadway, New York City.

Amphibians

All nature is so full that that district produces the greatest variety which is most examined.

—Gilbert White, Natural History of Selborne.

The group of back-boned animals next above the fishes is the Amphibians, which includes the frogs, toads, salamanders,[7] and their relatives. The name "amphibian" refers to two modes of life as shown by most of the frogs and toads. A good example is the Common Toad, whose eggs are laid in the water. These eggs hatch out not into toads, but into tadpoles, which have no legs and which breathe by means of gills, as the fishes do. They grow rapidly, develop a pair of hind legs and then a pair of front legs, while the tail and gills are absorbed, all within a little more than a month from the time the eggs are laid. During this change a pair of lungs is developed, so that the toads breathe air as human beings do. The eggs of toads and frogs may be collected in the spring in ponds, and this remarkable change from the egg through the tadpole stage to the adult form may be observed in a simple home aquarium. Toads' eggs may be distinguished from those of frogs by the fact that toads' eggs are laid in strings, while frogs' eggs are laid in masses.

TOAD
A valuable animal in the garden because of the insects which it eats. Range: Eastern United States. Photograph by Herbert Lang.

Every Girl Scout should know the song of the toad. William Hamilton Gibson says it is "the sweetest sound in nature." (Sharp Eyes, p. 54.) If you do not know it, take a lantern or electric flash-lamp after dark some evening in the spring at egg-laying time, and go to the edge of some pond and see the toad sing. Notice how the throat is puffed out while the note is being produced.

BULLFROG
The largest of our frogs, remarkable for its sonorous bass notes. Range: Eastern United States westward to Kansas. Photograph by Herbert Lang.

The belief that warts are caused by handling toads has no foundation in fact.

The toad is a valuable friend of the gardener, for it feeds upon a great variety of destructive insects.

The life of our Salamanders is very similar to that of the frogs and toads. The eggs hatch out into tadpoles, then legs are developed, but the tail is not absorbed. Unlike the frogs and toads, the Salamander keeps its tail throughout life, and in some kinds of Salamanders which spend all of their time in the water, the gills are used throughout life. Salamanders have various common names, some being called newts, others water-dogs or mud-puppies. The mud-eel and the Congo "snake" of the Southern States, and the "hell-bender" of the Ohio valley and south are all Salamanders. The belief that any of the Salamanders is poisonous is a myth and has no basis in fact.

SPRING PEEPER
The note of this piping hyla is a welcome sound about the ponds and swamps in early spring. Range: Eastern United States. Photograph by Herbert Lang.

Reptiles

Reptiles include Alligators, Crocodiles, Turtles, Lizards and Snakes. It is commonly said that reptiles are cold-blooded. This means that the temperature of their blood varies and is the same as the surrounding medium. The temperature of an Alligator that has been floating with its nose out of the water is the same as the surrounding water. The temperature of a turtle in the winter time is the same as the mud in which it is buried, while in the summer time it is much higher. What is true of the reptiles in respect to temperature is also true of Amphibians and Fishes. However, this is not true of Birds and Mammals, for these have a uniform temperature so high that they are called warm-blooded.

GILA MONSTER
So called from the Gila River in Arizona. The only member of the lizard family known to be venomous except the very similar crust-lizard found in Mexico. Range: Desert regions of southern Arizona and New Mexico.

In the United States there is but one species of Alligator and but one species of Crocodile, both limited to the Southeastern States.

There are about fifty kinds of Turtle and Tortoises in North America, some of which live on the land and feed largely upon plants, e. g., the Common Box Turtle, found from the New England States to South Carolina and westward to Kansas, and the Gopher Tortoise of the Southern States. Others are aquatic, like the Painted Turtles, which are found in one form or another practically all over the United States.

Many of these reptiles are highly prized as food, e. g., Diamond-backed Terrapin, Soft-shelled Turtle, Snapping Turtle and Gopher Tortoise.

COMMON BOX TURTLE
Range: Eastern United States

There are about one hundred species of Lizards in North America, the greatest number being found in the drier parts of the continent. Of this whole number only two species are poisonous, and only one of these, the Gila Monster, is found within the United States, being confined in its range to desert regions of Southern Arizona and New Mexico.

The Blue-tailed Lizard or Skink, which occurs from Massachusetts to Florida and westward to Central Texas, is commonly believed to be poisonous in the Southern States, where it is called the Red-headed "Scorpion," but this is one of the popular myths still too common among intelligent people.

The Glass "Snake" of the Central and Southern States is a peculiar lizard in that it has no legs. That it is able, after being broken to pieces, to collect itself together again and continue to live is another old myth.

DIAMOND-BACKED TERRAPIN
Range: Salt marshes of the Atlantic Coast and Gulf of Mexico from Massachusetts to Texas.

About a dozen kinds of Horned "Toads" are found in the western portions of the United States. Although toad-like in the shape of their bodies and in some of their habits, they are really lizards.

The American Chameleon or "Green" Lizard, which ranges in this country in the coastal regions from North Carolina to the Rio Grande River, has a remarkable power of changing the color of its skin through shades of brown, gray, and green. In fact, it is said to rival or possibly excel the true chameleons of the Old World.

For treatment of the Snakes see [Woodcraft], Section XIII.

FISHES
"It is not all of fishing to fish."

PADDLE-FISH
So-called from the paddle-like or spoon-shaped snout. Eggs used for caviar. Range: The Mississippi River and its tributaries.

The fishes are the lowest of the true vertebrates or animals with backbones, and all live in the water. They do not have lungs, but breathe through gills on the sides of the head. They are cold-blooded animals; i. e., the temperature of the blood is the same as that of the water in which they are living. Fishes are found in both fresh and salt water all over the world and have adapted themselves to many conditions; for example, certain fishes have lived in caves so long that they are blind; some live in the coldest water, while others can revel in the heat of the hot springs.

COMMON CATFISH
The barbels which suggest the whiskers of a cat are responsible for the name. This fish has no scales. Range: Eastern and Central United States.

Many fishes are valuable as food and the fisheries are extensive industries, in which large sums of money are invested.

There are four great groups of fishes:

1. The sharks and rays, with cartilaginous skeletons.

2. The ganoids of which the sturgeon and garpike are examples, with heavy plates or scales.

3. The bony fishes—salmon, pickerel, mackerel, cod, halibut, etc.

4. The lung fishes, that live partly in air.

SHOVEL-NOSED STURGEON
This fish is covered with bony plates instead of scales. The roe is made into caviar. Range: Upper and middle Mississippi Valley.

There are many species of sharks. Among the more common ones in Atlantic waters are the Smooth Dogfish which have pavement-like teeth; the Sand Shark with catlike teeth; the Hammerhead Shark with its eyes on stalks. The near relatives of the sharks are the Skates. The most common example of the ganoid fish is the sturgeon, which is heavily clad with a bony armor. Most of the fishes that we find, however, belong to the third group, i. e., bony fishes. Among the salt-water species, the cod, the halibut, the mackerel, and the bluefish are especially valuable as food. Of the salt-water fishes that go up the rivers into fresh water to breed, the salmon and the shad are widely known. Of a strictly fresh-water fish, the sunfish and catfish are very common. Among the game-fish are the trout, bass, pickerel, and salmon.

For those who live in cities, a convenient place to begin the study of fishes is in the fish-market. Here we may learn to know the common food-fishes by name, and to know many interesting things about them. If there is a Public Aquarium or a Natural History Museum in your city, you can use it in connection with the fish-market. Especially valuable in Museums are the habitat groups of fishes, that is, those in which the fishes are shown in their natural surroundings. But, best of all, the place to study fishes, as is true of all other animals, is out-of-doors in their native haunts. With your dip-net or hook and line, catch the fish, and then by the aid of one of the books listed below find out what its name is. Then, by observation of the fish see what is interesting in its life-history. Find out where the mother-fish lays her eggs. Does either parents guard them? Has the fish any natural weapons of defense? If so, what are they? Does either parent care for the young after they are hatched? What does the fish feed upon? In what way is the fish protectively colored? In the study of fishes, an interesting means is the home aquarium. Any Girl Scout can easily learn how to install and maintain a balanced aquarium, that is, one in which the water does not have to be changed and in fact should not be changed. In such an aquarium one may keep and study a great variety of fishes. Some of our local fishes, such as young catfish and suckers, will prove fully as interesting as the goldfish and many other animals besides fishes will thrive in a small aquarium, such as tadpoles of frogs, toads, and salamanders, adult water-newts, soft-shelled turtles, snails, and water-beetles and nymphs of dragon-flies.

HAMMERHEAD SHARK
The eyes are on the ends of blunt stalks, or extensions of the sides of the head, which suggest the name. Range: All warm seas, north to Cape Cod.

A GARDEN UNDER WATER
Starfishes, Crabs and Sea-anemones

SQUID
Member of same family as Octopus, and is related to the Oyster. Has ink bag for protection.

Animals Without Backbones

In general the Invertebrates are animals without a backbone; that is, they do not have an internal supporting skeleton of bone, as does the dog or cat. Compared with mammals or birds, they are all small and some are so very tiny that they can be seen only with a very powerful microscope. Most of them live in the water or in the mud or sand under the water. Hence the best place to get acquainted with them is along the seashore or near some lake or stream.

There are several different groups of Invertebrates and between these groups there are greater differences of structure than there is between a horse and a hummingbird. The principal groups are:

1. The Protozoa, or one-celled animals (nearly all microscopic).

2. The Sponges.

3. The Jellyfishes, Sea-anemones, and Corals.

4. Worms of several groups.

5. Starfishes, Sea-urchins, and Sea-cucumbers.

6. Segmented Worms.

7. Crabs, Lobsters, etc.

8. Oysters, Snails, and Octopi.

9. Insects and Spiders.

SNAILS AND THEIR TRACKS ON THE BEACH
—Photograph by Mary C. Dickerson.

Seashore Life

Because of their connection with our industries or our food supply, some of the Invertebrates are familiar to all; for instance, sponges, corals, starfishes, crabs, shrimps, lobsters, clams, and oysters. Others are seldom seen unless one takes pains to look for them.

JELLY FISH

All life comes from pre-existing life. So every animal living to-day has come from some other living animal and every plant living to-day has come from some other previously living plant. It is believed that the first forms of life came from the water. At any rate, the oldest and lowest forms of life to-day, the Protozoa, are found in the water. As these are nearly all very minute and can be studied only with a microscope, they are omitted from the suggested field work.

ANIMALS OF THE WHARF-PILES
Habitat Group in the American Museum of Natural History

All who have access to the seashore have a wonderful opportunity to study the Invertebrates. The long stretches of sandy beach, the sections of shore covered with water-rolled pebbles and stones, even the steep, jagged cliffs, are all pebbled with these animals of the sea. Twice every twenty-four hours the sea water creeps slowly up the beach until high water is reached, and twice every twenty-four hours it recedes again toward the ocean. It is therefore about twelve hours from one low water to the next. On a gently sloping beach, the distances between the high water mark and the low water mark may be many hundreds of feet, while on a steep beach or a straight cliff this area may be only a few feet in width. It is this area between the high and low water marks that is the haunt of many Invertebrates. These are animals that can live if they are not continually covered with water. Here are the rock barnacles, the soft clams, crabs of many kinds, beach fleas, numerous sea worms in their special houses, snails, and hermit crabs. Others will be found in the pools between the rocks or in the crevices of the cliffs, which as the tide falls becomes great natural aquaria. Here will be found hydroids, sea-anemones, starfishes, sea-urchins, barnacles, mussels. In the shallow water, crabs and shrimps are crawling along the sandy bottom or are lying concealed in the mud, while schools of little fishes scoot across the pool. If a fine silk net is drawn through the water and then emptied into a glass dish a whole new world of creatures will be revealed—jellyfishes, ctenophores, hydroids, eggs of fish, tiny copepods, the larvae or young of sea-urchins, starfishes, or oysters. If an old wharf is near by, examine the posts supporting it. The pilings seem to be coated with a shaggy mass of seaweed. Scrape some of this off and put in a dish of water. Sea-spiders, starfishes, hydroids that look like moss, sea-anemones, many varieties of worms, mussels and crabs are all living here.

UNDER THE SEA BED
Marine Worms, Whelk, Pecten or Scallop and Periwinkle

Begin your study of these seashore animals with a stroll along the beach. Examine the windrows of seawrack or seaweed. Whole troops of sandhoppers rise ahead of you. Oftentimes animals from distant shores or deep water will be found. The empty shells have many a story to tell. The papery egg-cases of the periwinkle remind one of a beautiful necklace. The air bubbles rising from the sand or mud as the wave recedes mark the entrance to the burrows of worms. Stamp hard on the sand. A little fountain of water announces the abode of the soft clam. Watch the sand at the edges of the rippling water. The mole-crab may be seen scuttling to cover. In the little hollows between rocks a rock-crab or a green-crab may be found on guard.

WHELK (FULGUR CANALICULATA) AND EGG-CASES
Common Mollusk Found on Sandy Shores Along the Atlantic Coast of the United States.

For collecting in the pools and shallow water a fine-meshed net is desirable. Many of the animals can be caught and placed in glass dishes of sea water for close observation.

Group showing a starfish attacking an oyster; soft shelled clams; hermit crabs; fiddler crabs, etc.

A few animals that may be found at the seashore:

Rocky Shores—Hydroids on the rock-weed, rock-barnacles, snails, amphipods, lobsters, and oysters.

Sandy Shores—Worms, in tube houses, mole-crab, sand-hopper, egg-cases, whelks, shrimps.

Muddy Shores—Snails, clams, worms of many varieties, mud-crabs, hermit-crabs, blue crabs, scallops.

Wharves and Bridges (on the piling)—Sponges, hydroids, sea-anemones, ascidians, starfishes, sea-urchins, worms.

On the shores of lakes, ponds, and streams will also be found many invertebrates.

HUMMINGBIRD MOTH
Range: Eastern North America. The larvae or caterpillars of this moth feed upon virburnum, snowberry and hawthorn.

SEVENTEEN-YEAR CICADA OR SEVENTEEN-YEAR "LOCUST"
Range: Eastern United States. Pupae emerging from the ground. Detail from Group in the American Museum of Natural History.

Insects play an important part in Nature's activities. From the point of view of man some are beneficial and some are destructive. In the former group may be mentioned the Dragonflies which feed upon mosquitoes, the Cochineal insects of Mexico, which furnish a dye-stuff, the Lady-bird beetles, which in the larval stage feed upon plant lice; the scale insects of India, which furnish shellac; the Bumblebees, which cross-pollinate the clover, and the Wasps, which fertilize the figs. Dr. Lutz says that the manna which fed the Children of Israel was honeydew secreted by a scale insect, and that it is still eaten.

SEVENTEEN-YEAR CICADA OR SEVENTEEN-YEAR "LOCUST"
Range: Eastern United States. The pupa climbing tree trunk. Then it bursts its horny outer skin and crawls out an adult.

The Silkworm and the Honey-bee have been domesticated since prehistoric times, the former supplying a valuable fiber for clothing and the latter an important article of food.

Among the injurious insects a few may be mentioned: the House Fly or Filth Fly, which may carry disease germs on its feet to the food that we eat; the mosquitoes, which transmit yellow fever and malaria, the rat flea, which carries bubonic plague; the weevils, which destroy rice, beans, chestnuts, etc., and the plant lice, or aphids, which, by sucking the juices from ornamental and food plants, are among the most destructive of all insects.

There are so many insects in the world that we cannot hope to learn of them all, even if we wanted to do so, but most of us wish to know the names of those that attract our attention, and to know what they do that is important or interesting. There are approximately 400,000 species or kinds of insects known in the world; that is, about three times as many as there are species or kinds of all the rest of the animals in the world put together. This fact should not hinder us from making a start and becoming familiar with the interesting habits of a few of the insects about us.

The eggs of the Monarch Butterfly may be collected upon the milkweed and brought in, so that the whole life history or metamorphosis of this beautiful insect, from the egg through the larva or caterpillar stage and the pupa or chrysalis stage to the adult butterfly, may be watched. The larvae or caterpillar must be supplied daily with fresh milkweed leaves. Other butterflies and moths and many other insects may be reared in the same way by supplying the larvae with suitable food. If we should find a caterpillar feeding upon the leaves of a maple tree we should continue to feed it maple leaves if we wish to rear it. Silkworms will eat the leaves of Osage-orange, but they seem to prefer mulberry leaves.

Cocoons of moths may be easily collected in winter after the leaves have fallen, and brought in and kept in a cool place until spring when the coming out of the adult moths will be an occurrence of absorbing interest.

"A GATHERING OF MONARCHS"
Monarch Butterflies resting during migration. The Monarch ranges all over North and South America and it migrates like the birds. Photograph of group in American Museum of Natural History.

The spiders, although not insects, are interesting little animals. See how many types of webs you can find. Mention a few insects which you know to be preyed upon by spiders. Mention one insect that catches spiders and stores them away as food for its young.

TRACKS OF THE GLACIER
North America at the time of the maximum stage of the Great Ice Age, showing area covered by ice. (After Chamberlin and Salisbury). Photograph used by courtesy of Henry Holt & Co.

THE KING OF THE NORTHLANDS

GEOLOGY

Finds tongues in trees, books in the running brooks,
Sermons in stones, and good in everything.

—Shakespeare, As You Like It.

The Structure and History of the Earth

There is nothing eternal about the earth except eternal change, some one has said. It requires only a little looking about us to see that this is true. The earth is not as it was in the past. Every shower of rain changes or modifies its surface. And many other and some very great changes have occurred during the past few millions of years. During one age, the coal was formed of plants that grew luxuriantly on the earth's surface. At one period in the development of the earth there were many kinds of invertebrate animals, but no animals with backbones. Later, the vertebrates appeared. At one time the whole Mississippi Valley was under the water of the sea. ("The Story of Our Continent," by N. S. Shaler. Ginn & Co.). These statements suggest just a few of the things that have been going on in the history of the earth. By the study of Geology we can learn much more about it, and we should supplement our study of books with the more important actual observation of conditions out-of-doors. To those living in that part of North America, which is shaded in the map on [page 451], the easiest and most natural approach to the subject of the structure and history of the earth is by studying the effects of the continental glacier which formerly moved down over this region.

Tracks of the Glacier

When we see the foot-prints of an animal in the mud or in the snow, we are sure that an animal has passed that way at some previous time. Those who live in Canada or northern United States (See map [page 451]) can be just as sure that a great glacier or ice-sheet formerly moved down over northern North America, by the tracks it has left. Although it is estimated by geologists that between 10,000 and 40,000 years have elapsed since the Great Ice Age, these tracks or evidences can still be seen by any one who lives in this region or who can visit it. The principal ones are: (1) Boulders or Lost Rocks which were brought down by this glacier; (2) The Glacial Drift or Boulder Clay which covers nearly all of the glaciated region; (3) Scratches on the bed-rock which show the direction the glacier moved.

Notice in the field the size and shape of the glacial boulders, where they are found, evidence of the place where the glacier melted off (terminal moraine). Do these boulders increase or decrease in size as we go south over the glaciated area? Can you discover any place where they can be traced back in their native ledge? Present-day glaciers, like the Muir Glacier in Alaska, can be seen transporting boulders and drift just as this great prehistoric ice-sheet must have done.

The drift which consists of clay mixed with pebbles, cobblestones, and boulders, varies greatly in depth. In some places there is none, while at St. Paris, Ohio, it is 550 feet deep. It probably averages 100 feet thick or less.

In your locality note the depth of the drifts in cuts made naturally by creeks and rivers or those made artificially for railroads. Oil-wells furnish evidence on this point. Collect a few good examples of scratched or glaciated pebbles or cobblestones which are abundant in the drift. These were scratched while frozen in the bottom of the glacier and pushed along on the bed-rock under the weight of the ice above.

Collect ten different kinds of rock from the glacial boulders and drift,—there are more than one hundred kinds to be found,—and with the aid of some such book as "Rocks and Rock Minerals," by Louis V. Pirsson (John Wiley & Sons) or "Common Minerals and Rocks," by Wm. O. Crosby (D. C. Heath & Co.) try to identify them.

All soil is composed of disintegrated or decayed rock. And it has been observed that the soil of northern North America is foreign to the bed-rock. Therefore it must have been transported from some other place. The glacier did this huge piece of work. The soil of southern United States contains no boulders or cobblestones and has been formed by the disintegration and decay of rocks in place.

Observe glacial scratches and grooves on the bed-rock, those on Kelley's Island in Lake Erie are famous.

Agassiz was the first to realize that it was a glacier that did this stupendous piece of work, and this conception or discovery greatly added to his fame. It is now easy for us to find the evidences and to enjoy their interpretation.

In fact, the Greenland ice-sheet is a remnant of this prehistoric continental glacier.

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