The Fal, which is the most considerable river in the centre of the county, rises about two miles west of Roche Rocks, and after a course of 12 miles, meets the tide below Tregony, and passing Tregothnan Park, joins Truro and St. Clement’s Creeks, which are navigable to Truro Quay and Tresilian Bridge; from its junction with those creeks, after flowing four or five miles, it forms the principal branches of Falmouth Harbour, named Carrick and King’s Road.
The river Alan or Camel, rises on the north-east side of the county, near Camelford, and after a circuitous course of 12 miles, becomes navigable for barges at Egleshale, near Wadebridge, from whence it flows into the harbour of Padstow. On all these rivers, as well as others of less note, great quantities of sea sand are carried in barges for manure, and sold to the farmers at a very reasonable rate.
The most considerable lake in Cornwall, is the Loo Pool, near Helston, and which is about two miles long and a furlong wide, formed of a bar of pebbles, sand, and shingles, forced up against the mouth of the creek, by the south-west winds; but in the winter time, the whole valley between the sea and Helston, is frequently covered with water.
Dosmery Pool, is a piece of water about a mile in circumference, lying in the parish of Alternon, on the borders of St. Cleer parish, and said by Leland, to be 15 fathoms deep, but which, upon trial, a few years back, was found to be only nine feet. It is formed and supplied by water which drains from the neighbouring hills.
Between Budock and Falmouth is a piece of water, near half a mile in length, and secured from the sea, by a bar of sand and shingles, called Swan Pool, from the circumstance of its having had many swans kept on it some years ago.
The Soils of Cornwall chiefly consist of three species: first, the black growan or gravelly; second, the shelfy or slaty; third, loams differing in texture, colours, and degrees of fertility.
The first abounds in the high lands, and consists of a light, moory, black earth, intermixed with small particles of granite or gravel. The earthy parts of this are so exceedingly light, that in a dry summer, as Dr. Borlase observes, the sun quickly exhales its moisture, and in a wet summer or winter, much of the vegetable soil is washed from the tilled grounds. This soil is in general very productive, and fit for any kind of grain. The shelfy or slaty soil is far the most prevalent, and is distinguished by this name from having a large proportion of the schistus, or rotten slaty matter mixed with the light loam, of which its soil is composed. With sand and more viscuous earths, it makes an excellent compost, and produces great crops of wheat and barley. In congenial situations, barley has frequently been sown, reaped, and threshed, in less than nine weeks. This soil is not unfrequently mixed with quartz, provincially called spar, and according as this prevails, its value is lessened. When a dun or ironstone is found, it is considered a fortunate circumstance, being a certain indication of the incumbent soil.
Of the Loamy Soils, there are many very rich and fertile patches, interpersed in different parts of the county; and the low grounds, declivities, banks of the rivers and town-lands are composed of them. Some of these are incumbent on a subsoil of clay, and partake more or less of it in their composition. With respect to Clays, Cornwall presents endless varieties; good bricks are made from some of them, and in the parish of Lelant, there is an excellent species for making furnaces and ovens. A clay of a slaty nature, but soapy to the touch, is found near Liskeard, and has fertilizing powers; but the Serpentine, with veins of steatite, near the Lizard, is the most curious of all the earthy substances found in Cornwall, although very little of it has been used for some years in the porcelain manufactures. Large quantities of a fine white clay, found in the parish of St. Stephen near St. Austell, is exported annually, and is now become an important article of commerce.
The mineralogical substances of Cornwall are more abundant than any other county in England, and the variety and beauty of them affords an abundant source for the scientific enquirer. Of the stones most entitled to precedence, is the granite, or moor stone, which abounds in great quantities in almost every part of the county. Granite is an aggregate of felspar, quartz, and mica, and is found of different colours and texture. Most of the churches and gentlemen’s seats in the county are built with this stone, also the Waterloo Bridge in London, and which was exported at a very great expense. It is frequently cut into pillars, as supporters to buildings, and is very serviceable as gate posts, bridges over rivers, rollers, troughs, and many other purposes.
Another species of stone very prevalent in Cornwall, is distinguished by the name of Killas. It is a schistus, and forms the most considerable substratum in the county. It varies in texture and colour, some being hard, others more pliable and laniated, and of a blueish yellow, and ferrugineous brown; but either forms an excellent material for building.