This was the warm stage which succeeded the glacial Illinoian. Between the Illinoian and the Wisconsin there passed a long period of time. It is now believed that it was interrupted by the Iowan ice-sheet, but this appears not to have lasted long nor to have occupied any considerable area. Associated with it in some way was the accumulation of much loess. This was formerly supposed to have been deposited to a large extent at least during the Sangamon; but, as Leverett informs me, it appears to have been laid down at a time nearer the Wisconsin than the Illinoian. This Iowan drift and the loess has been the subject of a special investigation by Alden and Leighton (Iowa Geol. Surv., vol. XXVI, pp. 49–212). Few vertebrate fossils have been found in the loess. Their bones may have been dissolved out by the percolating rain-water, and yet the delicate shells of land mollusks are abundant. A collection which the writer regards as belonging rightfully to the Sangamon was made at Alton, Illinois, many years ago, by William McAdams. A list of the species and an account of the geological conditions connected with it are presented on page [339]. The remains appear to have accumulated in a pond on the Illinoian drift and to have been covered by loess. The horse was yet in existence, as well as the deer Sangamona and the antelope Taurotragus americanus. Two-thirds of the 15 species are extinct. A smaller number of species have been collected near Kimmswick, just below St. Louis, Missouri. The remains found in a cave in Bexar County, Texas, are believed to belong here (Hay, Proc. U. S. Nat. Mus., vol. LVIII, p. 129). It is, however, in the Alleghany Mountains that most of the vertebrates have been collected which the writer refers to the Sangamon stage. These have been found in caves and fissures from northern Pennsylvania to northern Alabama. Unfortunately, although mostly discovered several years ago, some of these collections have not yet been well studied and have not been accessible to the writer. They contain two or three species of horses, two or three genera of peccaries, tapirs, the deer Sangamona, the antelope Taurotragus, and one or more species of saber-tooth tigers. Half or more of the species are extinct. To the writer these assemblages seem to fit into the history nowhere so well as into the Sangamon stage.

Another assemblage that probably belongs here is that made at Toronto (p. [282]). This indicates a warm climate, since the pawpaw and the osage orange grew there.

XV. The Peorian Interglacial Stage.

This is the interglacial interval between the Iowan glacial and the Wisconsin. It was probably not of long continuance and is chiefly remarkable for the deposition of loess. This has not furnished any important collections of vertebrate fossils. The type locality for the Peorian stage is a locality east of Peoria, Illinois. Leverett (Monogr. XXXVIII, U. S. Geol. Surv.) mentions several cases in which old soils believed to belong to the Peorian were observed in Illinois. None of these has furnished vertebrate fossils. It is usually difficult to distinguish the Sangamon from the Peorian soils.

XVI. The Wisconsin Glacial Stage and the Wabash Beds.

The next stage which furnishes abundant vertebrate fossils is the Wisconsin. These remains are found most abundantly in the old soils and mucks which accumulated in the swamps, ponds, and lakes left on the uneven surface of the Wisconsin drift as the ice retired. To such deposits the writer has given the name Wabash beds. They are often called post-glacial deposits; but that term ought in strictness to be applied only to deposits of the present epoch. They may be called Late Glacial, but that expression has been used for the drift and moraines produced by the second half of the Wisconsin glaciation. It might be better to use for the divisions of the Wisconsin the terms Lower and Upper.

In the late Wisconsin, or the Wabash, deposits there may be found remains of any of the existing animals of the region; also often the bones and teeth of mammals now living in more northern regions. Besides these, there may occur the relics of animals which were able to endure the rigors, changes, and competitions of the Glacial period, but succumbed at its end. These are, especially, two species of elephants, one or two species of mastodons, four or more species of musk-oxen, the moose Cervalces, one or more species of peccary, and the giant beaver.

XVII. On the Theory of the Pleistocene Terraces of the Coastal Plain.

The writer will discuss briefly the widely accepted theory that along the sea-coast from New Jersey to southwestern Texas there occurs a series of terraces and corresponding escarpments, three or more in number, representing successive emergences of the borders of the continent from the sea. The theory was first proposed by Dr. W. J. McGee (Amer. Jour. Sci., ser. 3, vol. XXV, 1888, p. 367; 12th Ann. Rep. U. S. Geol. Surv., pt. I, 1891, pp. 353–521). He included in the initial submergence not only the area occupied by the supposed Pleistocene terraces, but also the borders of the coasts to an elevation corresponding to the Lafayette (Appomattox) formation, which he referred provisionally to the late Pliocene. This submergence required a depression of the eastern half of the continent amounting to 500 feet or more. The theory was accepted especially by the geologists of Maryland in their excellent reports (Shattuck, Maryland Geol. Surv., Pliocene and Pleistocene volume, pp. 62–137, with maps). It has likewise been applied to the geology of Virginia (Clark and Miller, Va. Geol. Surv. Bull. No. IV, pp. 48–56, 179–189), North Carolina (Stephenson, N. C. Geol. Econom. Surv., vol. III, 1912, pp. 266–290), Georgia (Veatch, Geol. Surv. Ga., Bull. No. 26, 1911, pp. 35–50), as Okefenokee and Satilla; (Stephenson, ibid., pp. 425–445), Florida (Matson and Clapp, Fla. Geol. Surv., vol. II, 1909), and to Texas (Deussen, Water Supply Pap. U. S. Geol. Surv. 335, pp. 78–83).

Conspectus of the Geology and Vertebrate Paleontology of the Pleistocene.
1
Drift-sheets and other deposits.		2
Representative collections.		3
Disappearance of genera and species.		4
Characteristic genera.
Wisconsin Stage.
Atlantic to Pacific in Wisconsin, Illinois, Iowa, Indiana, Ohio, New York, New Jersey (Cape May, Trenton gravels), Ontario, Quebec, etc., Maine, Massachusetts.Made in swamps and old lakes on Wisconsin drift (Wabash beds) from Illinois to Massachusetts and Cape Breton Island. Leda clays, Canada.Megalonyx, Elephas, Mammut, Cervalces, Symbos, Boötherium, Mylohyus, Platygonus Bison occidentalis, CastoroidesExisting mammals, plus those of column 3
Peorian Stage.
Old soils between the Iowan and the Wisconsin drifts where the former is present. Reported by Leverett (Mon. U. S. Geol. Surv., vol. XXXVIII) from localities in Illinois. Usually hard to distinguish from Sangamon. Abundant loess in Mississippi Valley.Fossil mammals rarely found.None certainly known.Few recognized. In general, those of the Wisconsin.
Iowan Stage.
Known certainly only from Iowa and Wisconsin. Supposed to be present along New England coast, Gay Head to Maine.None.Mylodon, Tapirus, Equus, Taurotragus, Sangamona, Bison latifrons, B. antiquus, Ænocyon, Dinobastis, Smilodon, Smilodontopsis.None known; but in general those of the later stages.
Sangamon Stage.
Sangamon River, Illinois. Old soils just above the Illinoian drift. Some loess of this stage. Cave deposits in Texas and in the Alleghany Mountains.Alton, Illinois; Kimmswick, Missouri; cave in Bexar County, Texas; bluffs at Natchez, Mississippi; salt mine at Petite Anse, Louisiana; Cavetown and Corriganville, Maryland; Ivanhoe, Virginia; Whitesburg Tennessee; interglacial beds at Toronto, Ontario.None known to have become extinct during this stage.Mylodon, a few horses, tapirs, peccaries, Sangamona, Taurotragus, Symbos, Bison latifrons, B. antiquus, Elephas and Mammut.
Illinoian Stage.
In Illinois, Wisconsin, eastern Iowa, Indiana, Ohio. Supposed glacial drift from Long Island to Massachusetts (Montauk till, etc.).Conard fissure, Newton County, Arkansas. Otherwise none recognized.May include some accredited to the Kansan.Equus, Mylohyus, Symbos, Felis, Smilodontopsis, Dinobastis.
Yarmouth Stage.
Interglacial soils and mucks between the Kansan and Illinoian in Iowa and Illinois. Gardner clay and Sankaty from Long Island to Boston.Few vertebrates yet recognized. Skunk and rabbit at Yarmouth, Iowa.Not known.Few known. Doubtless those which became extinct during Illinoian and Iowan and later.
Kansan Stage.
Iowa, Missouri, Kansas, and northwestward. Loess overlying the drift; Jerseyan drift. New Jersey (may be Nebraskan); Pensauken. Jameco gravels on Long Island, New York, and Cape Cod, Massachusetts.Fossil vertebrates rarely found.Megatherium, Glyptodon, Stegomastodon, Anancus, Gomphotherium?, Elephas imperator, Eschatius, Camelops, Camelus, Hydrochœrus Aftonius, Leptochœrus, Trucifelis.Doubtless those in the later stages of this column and some of those of this stage in column 3.
Aftonian Stage.
Gravels and soils between the Kansan and the Nebraskan in Iowa, Missouri, Nebraska, and Kansas. Lake and river deposits in Nebraska and Oregon; river deposits, Pittbridge, Texas; asphalt beds near Los Angeles, California. Sands, etc. bearing vertebrate remains at or near sea-level from mouth of the Rio Grande to Sandy Hook, New Jersey.Along Missouri River in Iowa; Fossil Lake, Oregon; Grayson, Sheridan County, Nebraska; La Brea, California; Lake Lahontan and Walker River, Nevada; Lavaca and Galveston Bays, Texas; Peace Creek, Caloosahatchee River, and Vero, Florida; Brunswick and Savannah, Georgia; Beaufort and Ashley River, South Carolina; Neuse River, North Carolina; Fish House clay near Camden, New Jersey; Long Branch, New Jersey; Port Kennedy, Pennsylvania.None recognized. Probably some of those cited under the Kansan.Mylodon, Megalonyx, Megatherium, Glyptodon, Chlamytherium, Elephas imperator, Anancus, Gomphotherium, Tapirus, Equus, Hipparion, Camelops, Camelus, Bison regius, Hydrochœrus.
Nebraskan Stage.
Drift in Iowa and Nebraska beneath more recent drifts; Idaho formation, Idaho; New Jerseyan? and Bridgeton, New Jersey; Mannetto gravels, New York. Long Island, and Cape Cod, Massachusetts; “First Glacial” at Martha’s Vineyard; Arcadia marls, on Peace Creek; Alachuan clays and phosphates, and Bone Valley phosphates; marine marl bed at Vero; Coquina at St. Augustine, Florida; Quarantine Station, Southport, New Hanover County, North Carolina; Dismal Swamp, North Carolina and Virginia.Collections made in southwestern Idaho; “Oregon Desert,” Oregon; Anita, Coconino County, Arizona; Ringgold, Yakima County, Washington. In clays in Alachua and Levy counties; Dunnellon, Ocala, Brewster, and Mulberry, Florida. Horse at Martha’s Vineyard?.Gomphotherium floridanum, Protohippus, Parahippus, Procamelus, Teleoceras, Aphelops.Megatherium, Elephas imperator, Mammut, Gomphotherium floridanum, Protohippus, Parahippus, Hipparion, Equus, Tapirus, Teleoceras, Aphelops, Procamelus, Agriotherium, Canis, Trucifelis floridanus, Chasmaporthetes.
UPPER PLIOCENE—BLANCO, TEXAS; THOUSAND CREEK, NEVADA; ETCHEGOIN-TULARE, CALIF.
Upper Pliocene Stage.
Texas, Nevada, and California.Lists published by J. C. Merriam in Bulletin of Department Geology, University of California, vol. x, p. 425 (Etchegoin-Tulare); p. 425 (Thousand Creek); p. 434 (Blanco).Glyptotherium, Pliohippus, Tephrocyon, Hyænognathus, Ilingoceros.Glyptotherium, Megalonyx, Gomphotherium, Pliohippus, Hipparion, Teleoceras, Platygonus, Pliauchenia, Procamelus, Ilingoceros, Tephrocyon, Hyænognathus.