Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/152

 140 sight for an instant of general views, did not cease to collect in the most patient and judicious manner, observations of detail, which if not in sufficient number to enable us to explain all appearances, have nevertheless the immense value of serving as a compass, and thus preventing us from making retrograde steps in our researches after truth.

Though Mallyan is situated completely in the grauwacke slate, we find here and there in the neighbourhood loose blocks of serpentine, which indicate a transition country, and similar to that on the east side of the Lizard Point between St. Kevern and Menaccao. The cliffs from Mullyan to the neighbourhood of Loe Pool are the highest I have seen on the coast of Cornwall, especially near Pengwinian Point: they form a semicircular line, the regularity of which is broken by angular portions of the rock projecting in some places, and by fissures and indentations in others, exhibiting fine sections of the grauwacke. The continuity of the line is interrupted at Gunwalloe by the mouth of a small river; through this creek the sea-sand is carried at some distance into the interior of the country, covering the soil, and heaped together in some places so as to form little sand hills.

The cliffs become gradually lower as they approach Loe Pool, and the shore is covered with a very fine siliceous sand. At the mouth of the river Loe there is rather a curious fact, and worthy of some remark: the river forms a kind of reservoir at a little distance from the sea, which I found to be one hundred and sixty paces at low water, from which the water runs into the sea by a subterranean passage. The water in the pool is fresh, though the bar of sand between it and the sea is not more than twenty feet high. This shows that the tides do not rise very high, and the inhabitants assured me,