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the sea. The same author also reported to us that he Iiad disco- 

 vered similar gravel with recent marine shells overlying a peat 

 bog near Shrewsbury, in which were the remains of a submerged 

 forest. Mr. Murchison, however, having examined this spot, has 

 shown us that tlie supposed trees were stakes with sharpened points 

 driven into the ground, forming a woodwork which supported an 

 old road, and over these piles the shelly gravel or northern drift 

 had been afterwards spread artificially. I understand that Mr. 

 Trimmer is now fully aware of the mistake into which he had 

 fallen. 



From the evidence afforded by the shells, as well as by the indica- 

 tion of several newly discovered localities where they occur sixty 

 miles from the nearest sea-coast, Mr. Murchison infers that the tracts 

 covered by them must have formed the bed of the sea during the 

 modern period, and as the granitic drift occupying the high grovmds 

 east of Bridgnorth rises to the height of 500 or 600 feet, and thence 

 descends in a deltoid form into the Vale of Worcester, he conceives 

 that the sea also extended over the valley of the Severn from Bridg- 

 north to the Bristol Channel, so that there was then a strait sepa- 

 rating Wales and Siluria on the one side from England on the other. 

 The deposits observed by Mr. Strickland at Cropthorne and at 

 other points in the valley of the Avon, an eastern tributary of the 

 Severn, and which contain fluviatile and land shells, with the bones 

 of extinct quadrupeds, must, according to Mr. Murchison, have 

 been accumulated at the mouth of a river which flowed from the 

 east, or from the Cotteswold Hills, into the ancient straits above 

 alluded to, and into which the northern drift was prolonged. 



There are sections near Shrewsbury from which Mr. Murchison 

 has been enabled to deduce the relative age of the two alluvial for- 

 mations, the local or Welsh drift having in those places been found 

 covered by the clay and boulders of the northern drift. The latter 

 is, therefore, evidently of newer origin. As to the mode in which the 

 erratic blocks were transported, Mr. Murchison adverts to the 

 possible agency of ice-floes, and to the difficulty of imagining that cur- 

 rents of water alone, whether of rivers or the ocean, could have ex- 

 erted a force adequate to their removal to such great distances ; many 

 boulders of several tons in weight having been transported to more 

 than 100 miles from the nearest possible source of their origin. 

 He also infers from the position of the shells, gravel, and boulders, 

 that they were not washed, as has sometimes been imagined, by 

 one or more diluvial waves over preexisting lands, but were all de- 

 posited during the same period in the bed of the sea, which bed 

 was afterwards uplifted to unequal heights by movements of eleva- 

 tion of vmequal intensity — movements which, though so largely 

 affecting the physical geography of our island, must have taken 

 place within the modern sera. 



Mr. Edward Spencer has communicated to us the result of his 

 examination of the " diluvium " near Finchley, and the summits of 

 the neighbouring hills of Highgate and Hampstead. The gravel 

 there contains water-worn boulders of granite and porphyry, toge- 



