350 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 15, 



towards you ; and a section through such a bed, parallel to the line 

 of current, will show the pebbles with a general tendency to that 

 position. This is best exemplified when the stones are pretty large, 

 say, from six to twelve inches in length. 



Now I observed that the coarse shingle forming the Moor of Din- 

 net, in some of the fine sections laid open by the river, displayed 

 this feature, — showing, as I conceive, that it had been lodged by a 

 rapid current of water flowing down the valley. 



This water-rolled gravel I have examined along the Don, the 

 Ythan, the Deveron, the Findhorn, the Spey, the Tummel, the Tay, 

 and various other streams, and have found it everywhere to present 

 similar features. It seems to have been formed out of the pre-exist- 

 ing drift, being merely the stones and sand of that deposit, the clay 

 and muddy matter having been washed out. The fragments, how- 

 ever, have been rolled about so long, that their angularities have been 

 for the most part ground off and the whole reduced in size. This of 

 itself would seem to involve a considerable lapse of time, and to for- 

 bid the supposition of its formation being entirely due to any sudden 

 rush of water. 



It fringes the sides of many of the larger valleys to heights some- 

 times 200 feet above the adjoining stream, invariably capping all 

 the drift-deposits, but seems of older date than the submerged forests 

 and marine beds of the raised beach that lines the coast of Scotland 

 to a height apparently nowhere much exceeding 40 feet above the 

 present sea-level. 



It is also displayed in many places out of the way of all rivers, 

 and is frequently accumulated in long mounds behind masses of rock 

 that present bare and craggy faces on the opposite side. In valleys 

 the craggy side looks up the stream ; and in places where no river 

 exists it is presented in general to the interior, the tail pointing sea- 

 ward. 



Although much discussion has arisen about the drift and its trans- 

 ported boulders, less attention has been paid to this upper gravel ; 

 and as it is not peculiar to any one district, but occurs in all the 

 lower grounds and along all the lines of drainage of the country, 

 it deserves more investigation than has been yet bestowed on it. 

 That it is not the result of ordinary sea-action along the shallows of 

 former coast-lines is probable from several considerations : — 



First. From its position. It does not occur as belts or terraces 

 along the sides of the hills, but is chiefly developed in the middle 

 of depressed tracts, as if it had been projected down the valleys. 

 Now the action of the sea, or of the waters of a lake breaking upon 

 a shore, is to heave up sand and pebbles and pile them along its 

 margin. 



Second. From the arrangement of the pebbles, and the false-bed- 

 ding, — indicating, as I have already mentioned, the action of a current 

 flowing in one definite direction. 



Third. From this gravel being occasionally thrown together into 

 dome-shaped tumuli and abrupt hillocks of considerable height, such 



