To the west of Woodhall Spa, beyond the Stixwould-road, near the vicarage, and northward, the surface sand, in some parts, at the depth of a foot, or slightly more, hardens into an ironstone, so compact that tree roots cannot penetrate it. In root-pruning or manuring apple-trees, I have found the tap-root stunted into a large round knob, further downward growth being prevented by this indurated formation. This oxide of iron also pervades the sandy soil, in parts, to a depth of four or five feet, impregnating the water with ferruginous properties, so that it “ferrs” bottles, or vessels, in which it is allowed to stand for any length of time. In consequence, the water frequently has a dull appearance, although the iron may probably make it a wholesome tonic. The surface sand, which is of a still lighter character on the moor ground in Woodhall, and in Martin, Roughton, and Kirkby, contiguous to Woodhall, is what is technically called the “Old Blown Sand,” borne by the winds from the whilom salt marshflats of the Witham, when it was much wider than at present, and a tidal arm of the sea. It is comparatively a recent formation, yet abounding in fine particles, or pebbles, of quartz, and other elements of far earlier date; the larger of these are often rounded by tidal action. Below this surface sand we find, in many parts, a blue clay of varying depth. In a pit called Jordan’s pond, in an abandoned brickyard on the east of the road to Stixwould, it is at least 16ft. thick; also, in a large pit in Kirkstead, near Hogwood, some half-mile south-east of the Abbey Inn, which was dug to procure this clay, for “claying” the light super-soil, otherwise almost barren, it is many feet thick. Ammonites and other fossils are plentiful in it, often cemented together with veins of gypsum. Both these pits are mentioned in the Government Geological Survey (pp. 152, 153) of “The country around Lincoln.” Close by the latter pit the writer once found a curious fossil, which was for some time a puzzle to all who saw it. It is now in the British Museum, and was pronounced to be an Echinus crashed into an Ammonite.