46 Dr Black on some appearances connected with the 



of sand and gravel, containing pebbles and rounded fragments 

 of rocks from very distant localities, and which sometimes 

 affect a stratified deposition, but more generally an irregular 

 precipitation or subsidence of the same materials. To shew, 

 moreover, the nature of the different forces and of the physi- 

 cal circumstances then in action, it is to be remarked, that 

 while the fragments in the laminated talus are sharp and an- 

 gular, and evidently the disintegrated portions of the subja- 

 cent rocks, the deposited pebbles and small boulders in the 

 incumbent bed, commonly termed the diluvium, are composed 

 of rounded fragments from the surrounding geological forma- 

 tion, interspersed very frequently with rolled fragments of 

 transition or more primary rocks, which in many cases must 

 have been transported from a great distance*. 



However important and interesting the subject of these di- 

 luvial deposits may be, I only at present notice them with 

 the view of shewing their association with the beds of lami- 

 nated fragments — the subject of the paper, and of placing the 

 era of their deposition next in order, if not very near in time, 

 to the changes that have been effected upon the rocks in ques- 

 tion by previous congelation. 



From the foregoing exposition of the views which I in- 

 tended to submit, I hope I have succeeded in shewing, that the 

 disintegration and splitting up of the superficial beds of the 

 laminated rocks into loose and angular fragments were, by 

 every physical deduction, owing to the congelation of infil- 

 trated water through the pores and laminations of the affected 

 rocks ,- and that the present disposition of these disintegrated 

 fragments has been caused by the subsequent action of deep 

 currents of water of varying velocity and direction, and hold- 

 ing in suspension varying quantities of mud, sand, and gravel, 

 with occasional boulders. 



It may be thought that too much time and unnecessary lo- 

 gical deduction have been expended upon what appears so ob- 

 vious, but it has been expedient to proceed, in this instance, 

 with the argument strictly limited to the data before us, and 

 as if the science of geology had not formally existed ; for if 

 these data and appearances in nature could have been ex- 

 plained in any other manner, equally satisfactory, I would as 



