SKETCH OF HENRY CARVILL LEWIS. 405 



hollows over a strip of ground nearly a mile in width, forms a 

 continuous line of drift-hills (more or less marked) extending 

 completely across the State. These hills vary in height from a 

 few feet up to one hundred or two hundred feet, and, while in some 

 places they are marked merely by an unusual collection of large 

 transported bowlders, at other places an immense accumulation 

 forms a noteworthy feature of the landscape. When typically 

 developed this accumulation is characterized by peculiar contours 

 of its own — a series of hummocks, or low, conical hills, alternate 

 short, straight ridges, and inclosed shallow basin-shaped depres- 

 sions, which, like inverted hummocks in shape, are known as 

 kettle-holes. Large bowlders are scattered over the surface, and 

 the unstratified till which composes the deposit is filled with 

 glacier - scratched bowlders and fragments of all sizes and 

 shapes.' 



" From its lowest point in Pennsylvania, where it crosses the 

 Delaware, 250 feet above the sea-level, this terminal moraine ex- 

 tends indiscriminately across hills, mountains, and valleys, rising 

 over 2,000 feet above the sea in crossing the Alleghanies, and at- 

 taining the maximum of 2,580 feet on the high table-land farther 

 west, being there ' finely shown at an elevation higher than any- 

 where else in the United States.' 



" Preliminary outlines of Prof. Lewis's work on the glacial drift 

 of England, Wales, and Ireland are given by his papers in the 

 reports of the British Association for 1886 and 1887 ; and the first 

 of these also appeared in the ' American Naturalist ' for Novem- 

 ber, and the e American Journal of Science ' for December, 1886. 

 Their most important new contribution to knowledge consists in 

 the recognition of the terminal moraines formed by the British 

 ice-sheet, which Lewis traced across southern Ireland from Tra- 

 lee on the west to the Wicklow Mountains and Bray Head, south- 

 east of Dublin ; through the western, southern, and southeastern 

 portions of Wales ; northward by Manchester and along the Pen- 

 nine chain to the southeast edge of Westmoreland ; thence south- 

 east to York, and again northward nearly to the mouth of the 

 Tees ; and thence southeastward along the high coast of the 

 North Sea to Flamborough Head and the mouth of the Hum- 

 ber. It is a just cause for national pride that two geologists of 

 the United States — Lewis in Great Britain in 1886, and Salis- 

 bury the next year in Germany — have been the first to dis- 

 cover the terminal moraines of the ice-sheets of Europe. Like 

 the great moraines of the interior of the United States, those of 

 both England and Germany lie far north of the southern limit 

 of the drift. 



" Another very important announcement by Prof. Lewis relates 

 to the marine shells, mostly in fragments and often worn and stri- 



