XXXll PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



the valleys, of such deposits ; it being often clear that they only 

 appear so thickly strewed over the surface because the smaller portions 

 have been removed from the general mass, so that the blocks stand 

 out in more salient relief and apparently in greater multitude. 



In his observations on the recent formations in the vicinity of 

 Edinburgh, JVIr. James Nicol, after alluding to the general -saew taken 

 by Mr. Milne of that district, and remarking that the * till ' or 

 boulder clay has been usually regarded as exhibiting no marks of 

 stratification, and hence considered to have been the result of some 

 sudden and violent action, adduces facts, brought to light by sections 

 upon the Edinburgh and Leith Railway, which would show a gradual 

 accumulation of the clays, sands, gravels and boulders there cut 

 through. He refers the effects seen to continued and variable agents, 

 the clays and sands derived from the adjoining coal-measures, and 

 the boulders transported by ice and entangled in the roots of floating 

 trees. He points to the mode in which boulders, dropped upon a 

 mud-bottom, would descend irregularly into it, such mass of mud not 

 necessarily being stratified although formed gradually. 



Mr. Nicol considers that the facts observed would justify the con- 

 elusion that there had been elevation and depression of the sea-bottom 

 during these recent accumulations. With respect to the erratic 

 blocks, he thinks that, from the remarkable accumulation of them on 

 the Pentland Hills, this range of mountains may have stopped their 

 passage in a southward direction. A block of mica slate near Habbie's 

 How, supposed to have travelled forty miles, is estimated to weigh six 

 or eight tons. In some places they appear to form long and nearly 

 straight lines, having a N.N.W. and S.S.E. direction, " without any 

 reference to the present declivity of the gromid, except that they 

 seemed to become more numerous towards the summit of the ridge." 

 With regard to their occurrence above the level of the sea, Mr. Nicol 

 states, that upon one hill he found * these travelled stones ' particu- 

 larly abundant at the height of from 1500 to IGOO feet. 



Referring to certain sandstone and trap boulders at a higher level 

 than the usual mass of the same rocks in the adjoining country, though 

 there may be a few points at the same height, six or eight miles di- 

 stant, Mr. Nicol thinks that the configuration of the shores and rela- 

 tive distribution of land and water, if the land were depressed, would 

 scarcely be such as to justify the supposition that the blocks were 

 gradually raised to higher levels by means of coast ice as the land be- 

 came depressed. He rather supposes that there may have been unequal 

 elevations of land, carrying up the detritus, resting upon the dislocated 

 masses to different heights ; or so changing the relative levels that 

 the rocks whence the boulders were derived may then have been the 

 higher though now lower. In proof of this he quotes Mr. Milne as 

 enumerating 52 faults in this district "raising the strata to the south 

 5169 feet, and 37 others which raise them 2412 feet in the opposite 

 direction ; the most extensive slip having thrown the strata 400 to 

 500 feet downi to the north." Calling our attention to the kind of 

 movement now taking place in Scandinavia, Mr. Nicol remarks, that 

 if there was a similar movement between London and Anglesea, — 



