Sir H. H. Eoworth—The Baltic— The Ancylus Sea. 349 



Jara wall, already described, which overlies deposits containing 

 objects of the Stone age and remains of Pleistocene beasts, and 

 belongs therefore to the Zitorina time, is another proof that the 

 coming in of that period was accompanied by some cataclysm 

 involving a great rush of water. Those who have attributed this 

 great mound and rampart to the ordinary operations of the tide 

 have surely entirely given up induction in their pursuit of the 

 fantastic type of the doctrine of Uniformity, which is so fashionable 

 and so entirely metaphysical. Nilsson, who was the first scientific 

 man to critically explore the Jara wall, and who first really explained 

 its history, was most emphatic that it was no result of slow 

 secular movements of the sea, but of a cataclysm on a great scale, 

 probably coincident with the first inrush of the salt water to the 

 Baltic on the breakdown of the land-bridge. 



Turning from this great as of Southern Sweden to the asar of 

 Central Sweden and of the islands on the coast of Esthland, whose 

 upper beds are in some cases full of the debris of the Litorina sea, 

 we are constrained to the same conclusion. 



The as at Enkoping is a typical instance of an as in which the 

 upper layers are intercalated with beds containing shells dating from 

 the Litorina time. They occur chiefly along the portion of the as 

 extending from the church to the tilery, which runs from about 

 102 to 130 feet in height. The richest deposits of shells of the 

 beds occur on the south-eastern slope of the as, and at one place a 

 bed several feet thick occurs which is almost entirely composed of 

 broken shells of Mytilus edulis and Tellina balthica. This south- 

 eastern slope has an angle of from 20 to 25 degrees, and its upper 

 layers consist in descending order of — 



Feet. 

 Gravel with rolled pebbles .. . ... ... ... ... 2*5 



A bed of shells very argillaceous ... ... ... ... 3"0 



Sand and gravel with a few roUed pebbles I'O 



Clay without shells 0*5 



Sand and gravel with a few rolled pebbles 1*0 



Shelly gravel 0-3 



Sand and gravel with a few rolled stones 1"0 



Clay (styled glacial) without shells 0-5 



Sand and gravel with roUed stones 3*5 



Sand as far as the bottom of the trial pit 10-0 



On the north-west or opposite slope of the as the beds were — 



Feet. 



Fine gravel I'O 



SheUy gravel (chiefly with Jf2/i87Ms) 0'3 



Fine gravel ... ... 0-5 



0-2 



0-3 



0-7 



3-0 



So-called glacial clay with threads of sand ... . 5*6 



Sand 6-0 



The as is traversed by a valley leading from the tilery to the 

 plain from north-east to south-west, which is covered with typical 

 black clay containing Mytilus edulis, and in its upper layers is filled 



Shelly gravel without clay 

 Fine gravel ... 

 Shelly gravel without clay 

 Fine stratified sand . . . 



