lines of sand hills or dunes running along the coast. The solid geology of the country is composed of Triassic strata, but these are hardly ever visible, being covered over with beds cf glacial drift, often as much as 150 feet in thickness. Of these the lowest deposit seen Mr. De Rance calls the Till, It is a dark leaden-coloured clay, occurring at elevations of 200 feet and upwards only. It contains angular blocks of local origin, but no shells, and seems to have been formed by a sheet of land-ice. Upon if rests the Lower Boulder Clay, of reddish-brown colour, with many stones and boulders of lake-district rocks. It is finely exposed in the cliffs north of Blackpool. It is often stratified, and the stones, though striated, are partly rounded. Hence it would seem to tell us of a period of submergence when ice drifting from the north and east dropped its stony cargo in a shallow sea. Shells are not uncommon.
The Middle Drift Sand and Gravel marks a mild period, when the glacial cold hail decreased. It is sometimes as much as 70 feet thick, but is often absent. The molluscan remains show a mingling of northern and southern forms. It is commonly false bedded.
The Upper Boulder Clay is sometimes 100 feet thick. It is of a dull red tint, weathering on the surfaces or joints which may be exposed to the air, to a bluish-white. Large boulders are rare, but glaciated stones and shell fragments are common. Mr. De Rance believes that it was deposited under similar conditions to these of the Lower Boulder Clay, viz., from ice-floes in a shallow sea.
Thus the same triple division of the Drift is observable here as obtains on the east coast of England. The two, however, were not contemporaneous; and it is a pity that the same names should have been applied in each case to the different sub-divisions. Mr. S. V. Wood, jun., has shown the great probability that the Lancashire Drift is of later date than that of East Anglia. Is it possible that the east and west played a game of see-saw—the east coast first undergoing depression, while land-ice scoured out Lancashire? The Geologists of the Midland Counties must endeavour to aid in the solution of this problem, by tracking the deposits as far inland as possible.
In the latter part of his work Mr. De Rance treats at length of the Post-glacial deposits, especially peat; of the economic uses of the various deposits; the water supply; the deposition of shingle and sand forming the dunes; the action of tidal currents on the Lancashire coast; and various other interesting points. One valuable feature of the work is that abstracts are given of almost all the papers that have been written by previous authors on the subject. In an appendix (revised by Mr. Etheridge) the occurrence of the various shells which have hitherto been found in the glacial deposits of Lancashire is shown with great fulness, On page 132 we note a very obvious misprint of "clay" for "crag." Altogether, we evidently have in this Memoir the results of some years of really tough work—of work which only a love for science could make pleasant. Mr. De Rance may be congratulated in that he has given us a record of hard facts which will endure and serve as a work of reference for many a year to come.
