immense size. As it does not enter into the purpose of this memoir to treat of these deposits in any other view than as they are allied to Medical Statistics, I shall content myself with observing that, in many parts of the district, they are uncommonly fertile in the ordinary agricultural productions; that as well from the loose and friable nature of these, as from the uneven surface of the country, the general character of the soil is light and dry; and (with one or two very trifling exceptions) that marsh or bog land is entirely unknown. The only exception to this is furnished by a marsh between Penzance and Marazion, adjoining the sea, and partially saline, running parallel with the shore. It was formerly a mile in length and about a furlong in breadth, filled with reeds; but at the present time (1833) it is much lessened by draining and the beneficial encroachments of agriculture. On the northern shores, also, along the banks of the Estuary of Hayle and in the parish of Gwithian, there are some small strips of marshy land, but of very inconsiderable extent, and produced rather by the irruption of the sea water than the stagnation of the land springs. In the parishes of Lelant, Phillack, and Gwithian, there is a ridge of low hills of calcareous or shell sand, extending a couple of miles along the shore, and reaching inland from half a mile to a mile in different places. This accumulation of sand is evidently of comparatively recent formation, and must have been derived from the sea. It covers the native soil of the district, and is itself now covered and confined by a crop of the common sand weed or bent. Dividing these sand hills is the Estuary of Hayle, running
