36 



The Naturalist. 



drift, with partings of fine clay, and, midway in the section, we have a 

 well-defined bed of peat, with a maximum thickness of about 18 inches. 

 Another bed of peat, less clearly defined, and not so pure as the 

 former, is likewise present, the two beds having beneath them a band 

 of exceedingly fine clay, of a bluish grey colour, which evidently 

 corresponds to the "seating" or "floor clay" which is so invariable 

 an accompaniment of our coal seams. The beds of drift that enclose 

 the peat are alike in some of their main features, but very unlike in 

 others. In both, boulders, principally of foreign extraction, are in 

 great abundance, and give a striking appearance to both beds. In 

 the bed beneath the peat we have one or two bands of fine clay, coarse 

 sand, or grit pebbles, and boulders, while, as you will see, the upper 

 one, with some little variation, is made up of a very uniform arenaceous 

 clay, and a great number of boulders — a somewhat indifi'erent and 

 unprofitable material for making bricks. 



" The section of 14 feet before us gives but an imperfect idea of the 

 * thickness of these deposits as they existed at the time of their final 

 appearance above the sea, and we have not the means of determining 

 this thickness with any degree of exactness ; but, while remembering 

 that the brook which runs close by has worn out what we now know 

 as the valley of the Medlock, let us draw an imaginary line at right 

 angles to the trend of the valley, from, say Glodwick on the south to 

 Yorkshire-street on the north, and I think we may then hazard an 

 opinion that the bed of peat has at a former period in the remote past 

 been capped by from 50 to 100 feet of characteristic boulder clay, the 

 upper beds being known to the geologist as the "upper drift," and the 

 lower beds — stratified sand and gravel, with pebbles and boulders — as 

 the " middle drift," the lower and other deposits being wanting in this 

 neighbourhood so far as is known. 



" These deposits are said, with good reason, to be of marine origin ; 

 that the clay is but the half-dried mud of an old sea bottom ; that this- 

 clay, and a great per-centage of the boulders, pebbles, gravel, and sand 

 have been derived from distant districts, more or less northerly from 

 our present standpoint ; that these were brought and dropped here, 

 where we find them, by passing icebergs, assisted by shore ice sailing | 

 over the latitude in which we now live, and melting in the slightly 

 warmer waters and balmier breezes during the period known as the 

 " Ice Age," when the tops of our highest hills alone stood above the 

 level of a glacial sea, and when the plants now met with only within 

 or about the line of x^erpetual snow were denizens of this part of our 

 country, when the now extinct mammoth and the hairy rhinocerus, the 



