194 



THE GEOLOGIST. 



leaving behind it those significant terraces which may be seen on the slopes 

 of the hills abutting on the valleys of the Calder, the Hodder, the Eibble, 

 and the Irwell, from about Ramsbottom to its various sources. The con- 

 tents of these drift deposits also indicate several widely different conditions 

 of things. There must have been many quiescent periods, and also many 

 gradual depressions of the surface, during the formation of the various 

 coal-seams, and the deposition of the rocks and shales by which they are 

 overlaid. After the latest deposits there must have been a gradual up- 

 heaval, with occasional fractures, from the bed of a deep ocean, and, as the 

 bottom came nearer the surface, the more powerful would be the currents, 

 and hence the variable, but extensive denuding action of water which is 

 everywhere apparent. 



There is, however, good evidence that within the historic period the 

 coast of Lancashire, at least, has again undergone considerable depression. 

 In the times of the Romans there was probably no estuary of the Mersey. 

 Ptolemy does not include this now-important opening in his topography of 

 the coast. The dredging operations at Liverpool continually afford proofs 

 of recent land-surface ; and even hazel branches, containing nuts, were 

 dug up from a considerable depth during the formation of the Sandon 

 Dock. Along the shore from near Formby towards Preston, there are the 

 remains of an extensive ancient forest. Many trunks of trees were ex- 

 posed during the formation of the East Lancashire Railway, and are still 

 to be seen in the pools on each side of the road. The roots of these are 

 mostly below high-water mark, and in some places the trunks extend into 

 the sea ; but all of these must originally have flourished at a much higher 

 elevation. About Southport they are so numerous, that they have been 

 used to form ornamental fences for some of the gardens. 



At Blackpool, and on towards Fleetwood, the sea is washing down the 

 cliffs at the rate of about one yard in breadth per annum ; and tradition 

 states, on very probable grounds, that nearly half a mile, in breadth, of this 

 part of the Lancashire coast has disappeared within the last hundred and 

 fifty years. There are therefore strong reasons for supposing that Lanca- 

 shire is at present undergoing a gradual depression. In Scotland, on the 

 contrary, according to Mr. Geikie, the reverse operation is in progress, and 

 it may form an interesting subject for some speculative mathematical geo- 

 logist to inquire whether this apparent flexibility of the earth's crust is 

 due to internal local action, irregularly applied, or whether it is the natural 

 result of those mechanical laws which govern the earth when considered 

 as a comparatively solid film resting upon a fluid interior. 



In the discussion Mr. Hull said these discoveries of marine shells in the 

 drift were very interesting ; but there were also in the neighbourhood the 

 more recent gravels of the valleys. These are of later date, and, accord- 

 ing to the judgment of some, are most undoubtedly of the same age as the 

 Amiens and Thames valley gravels, and many others which are yielding 

 works of human art in different parts of Britain and the Continent; and 

 he thought it very important that the attention of local geologists should 

 be turned to the subject, because there is no reason, as far as we can see, 

 why our river-terraces here should not yield flint-implements, and the re- 

 mains of some of the extinct mammalia which appear to have been con- 

 temporary with man. With regard to the New Red Sandstone boulders 

 which Mr. Wilkinson says are 800 feet above the sea, of course it would 

 be improper to say they are not of this formation, but the identification is 

 very questionable. He did not think the New Red Sandstone in the north 

 of England attained to such a height. To suppose that boulders are car- 

 ried from a lower level to a higher is a very unlikely thing indeed, except 



