724 BEPORT — 1887. 



Another large ice-stream, which advanced from the Alps of South-western 

 Norway and the adjoining regions of Sweden to the eastern shores of England, 

 covered a great part of South-eastern Yorkshire, Lincolnshire, and the adjoining 

 counties. As it tilled up the Skagerack and crossed the North Sea, where it must 

 have met the Baltic-Dutch ice-stream, I have called it the Skagerack-North Sen 

 ice-stream. 



The northern part of Jutland is covered by the boulders which it brought from 

 Norway, especially the Rhomb porphyry from Christiania. Many years ago I 

 found this porphyry at Grimsby, and Mr. Helland, I believe, has met with it and 

 the syenite of Fredriksveem in Holderness. Just as the axis of the Baltic may be 

 prolonged to Norfolk, so a line drawn through the middle of the Skagerack will 

 meet the coast of Yorkshire. At Bridlington and elsewhere in Holderness the 

 beautiful ground moraines of this ice-stream — the casement or chalky clay of Mr. 

 Searles Wood, jun. — are open for study. As this great mass of ice grew in size, 

 whilst, owing to causes which I am just beginning to understand, the Baltic-Dutch 

 ice-stream diminished, most exti-aordinary phenomena resulted. The strata of the 

 chalk and other formations below the ice were partly broken up, moved along 

 from north-east to south-west, and e^Tn destroyed by it. Of these phenomena 

 Mr, Skertchly has given a graphic description.' 



The great chalky boulder clay of Mr. Wood is probably a moraine of the same 

 ice-stream. 



Mr. Wood describes extensive beds of sands underlying this clay to the south 

 as 'the Middle Glacial sands.' These, I suspect, are equivalent to the 'Diluvial 

 sand ' in Germany, and Alluvion ancien in the Alps, and were deposited by the 

 Glacial rivers from the ice-stream. 



That the great chalky boulder clay is a real ground moraine there seems to be 

 no doubt. According to Mr. Wood the great chalky boulder clay is later than 

 the Cromer beds. It seems really to be the case that the Baltic-Dutch ice-stream, 

 which deposited the Cromer series of beds, retreated before the greatest advance- 

 ment of the Skagerack-North Sea ice-stream. If, then, this ice-stream encountered 

 the Glacial beds at Cromer, the result would be such phenomena as the well-known 

 contortion of the drift there. The strata would be raised up and contorted in 

 every direction. As the bottom of the sea to the north-east of Cromer consists of 

 chalk, the ice could plough up and carry large masses with it and press them into 

 the drift as it contorted it. These boulders generally consist of reconstructed chalk 

 broken up into innumerable fragments cemented together again. One of these 

 boulders, that of West Runton (Woman Ilithe), is more than 600 feet long and 

 80 feet high, and has been pushed through the whole of the contorted drift from 

 top to bottom. Mr. Reid has expressed his opinion that only solid ice could cause 

 the contortions, but he does not consider how it may be explained that the same 

 strata which are formed bv ice should since have been disturbed by the same 

 agency. On the island of Hven, in Oresund, similar phenomena on a smaller scale 

 may be seen. There older Glacial beds are overlain by sands and clays, all formed 

 by a stream of ice from the north-east. Those were afterwards encroached upon 

 and partly destroyed by a later ice-stream from the Baltic, and phenomena similar 

 to those of the contorted drift at Cromer were produced. 



If the explanation which I have given is correct we have at Cromer evidence 

 that — 



1. The Baltic-Dutch ice-atremn deposited till on the Norfolk coast. 



2. This ice-sheet retreated while the Skngerack-North Sea stream advanced 

 southwards, so as to crush into these deposits, contorting them and forcing into 

 them masses of chalk torn from the sea-bed outside. 



7. On the Terminal Moraine near Manchester. 

 By Professor H. Carvill Lewis. 



A line of drift hills passing in a south-easterly direction close to the city of 

 Manchester is here described in detail, and held to be a portion of the terminal 



' In Professor Geikie's Tiie Great Ice Age. 



