Under Brown Willy is a pool called Fowey Well, which is traditionally held to be the source of the Fowey river. This however is not the case. It rises under Buttern Hill (1135 ft.) crowned by cairns, but as the Fowey Well has no outlet visible, it is supposed to decant by a subterranean stream into the river. Leaping down from the moors, the Fowey enters a wooded valley and, turning abruptly west, flows through another well timbered valley. Running beside the railway, and then turning sharply south, it passes the old Stannery town of Lostwithiel, to which the tide reaches, and plunging into a narrow glen with St Winnow on one side and Golant on the other, finally reaches the sea at Fowey harbour. There are two Looe rivers, one rising in the Bodmin moors receives the overflow of Dozmare Pool, and flowing deep below Liskeard receives the West Looe above the estuary. Duloe, which has a small but interesting circle of upright stones, stands between them and is supposed to be so called as between the two Looes. Before reaching Duloe the river has passed under St Keyne, famous for its Holy Well commemorated by Southey in a well-known ballad. There is no river of any importance till we reach the Fal. Rising on Goss Moor, not far from St Columb, and passing Grampound and Tregony, now an utterly decayed place, it meets the Tressilian and the Truro rivers, and all three, insignificant hitherto, suddenly acquire importance and spread out into the beautiful estuary of the Fal or Carrick Roads. Here are Penryn creek, Mylor creek, and Porthcuel harbour, commanded by the castle of St Mawes. None of these owe their importance to the sweet waters they bring down; all their value is due to the tide that flows up to Truro. The entrance to the Roads is found between Zoze Point and Pendennis Point, the latter at one time defended by a strong castle. Almost halfway between the points is the dangerous Black Rock, to which a former Trefusis conveyed his wife and there left her to be overwhelmed by the rising tide. Happily she was rescued by some fishermen. The Helford river is but a creek, noted for its oyster beds, into which a little stream dribbles. =6. Geology and Soil.= By Geology we mean the study of the rocks, and we must at the outset explain that the term _rock_ is used by the geologist without any reference to the hardness or compactness of the material to which the name is applied; thus he speaks of loose sand as a rock equally with a hard substance like granite. Rocks are of two kinds, (1) those laid down mostly under water, (2) those due to the action of fire.