Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/845

Rh AROUND THE ESTUARY OF THE DEE. 733 thickness above high-tide level) was found to extend to below low water. New Dock-sections near Bootle. — Further north than Egreraont, and on the opposite side of the Mersey, a series of extensive exca- vations are now in progress for the purpose of obtaining sites for new docks. They have been visited by several geologists ; and Mr. Morton, P.G.S. (in whose company I first saw these sections), has given a very brief account of them in the Geol. Mag. and in the Report of the British Association for 1876. Since then I have twice examined them, with the assistance of Mr. Sutcliffe, the acting en- gineer. An unwary visitor to No. 1 dock (going north) might at once conclude that the three drifts are there very strikingly displayed — the upper clay, middle stratified sand and gravel, and a great thick- ness of lower clay. What can be plainer ? he might say. A close and leisurely inspection, however, would show that his upper-clay had been artificially redeposited over a considerable thickness of Post- glacial sea-sand with numerous shells. The last time I examined these excavations a number of new and instructive sections were in course of being exposed (see fig. 3). In one spot a group of Pig. 3. — Section exposed in the second New-dock Excavation, April 1877. A. Postglacial sand, about 6 feet ; B. Upper Boulder-clay, about 12 feet, sepa- rated by a very distinct line from C, current-bedded middle sand and line gravel, a sprinkling of which is continued along the line of junction between the two clays ; D. Lower Boulder-clay, with an average thickness of about 12 feet ; E. Triassic sand and rock in situ. workmen stood on the partially uncovered and well-defined top of the lower clay, wielding spades, with which they speedily removed the upper clay*, while a throng of navvies, armed with picks, were attacking the base of the lower clay, which had been found to be too compact and stony to yield to spades. Towards its base the lower clay might be seen graduating both horizontally and verti- cally into masses of rounded gravel (partly consisting of erratic stones) or into sand ; and I was informed that in some places much sand had been found beneath it. The line of junction between it and the underlying Triassic sand and sandstone-rock could be easily traced. In several places (during a former visit) I found the middle shows more or less of the grey partings by which it is generally, but not always, characterized.
 * Where fresh faces have been exposed by clay-slips, the upper clay here