264 Sir H. H. Hoicorth — Surface Geology of N. Europe. 



north-and-sontla direction of these masses has necessarily been 

 determined by the chief physical features of Sweden, which consist 

 of frequent alternations of ridges of crystalline rocks and longitudinal 

 depressions. 



Murchison further points out how, when we get away from these 

 controlling ridges of rock, the asar depart from their typical form. 

 Thus, he says, in the tract between Danemora and the little seaport 

 of Kakholm, the asar, consisting of true rolled and sandy detritus, 

 are frequently arranged in circular heaps of about 100 paces in 

 diameter, each capped by coarse angular blocks. " Now, the water- 

 worn materials are, it will be observed, thus circularly grouped on 

 the lowest elevations in the midst of small plains or flats, from one 

 to two and three miles wide, loliich are devoid of those distinct longi- 

 tudinal encasing ridges of granitic rocks ivherebij the osar have usually 

 obtained their prevailing long and ridge-like character." 



In other cases, again, the asar simulate the oi'dinary "crag and tail" 

 formation, which, as Sefstrom urged, was the case in Sweden with 

 most of the smaller ones. A well-known instance is that at Kinne- 

 kulle, on Lake Wenern, which I have lately examined, and where 

 a train of sand and boulders, after the fashion of an as, is most 

 clearly, as Brongniart urged, the result of some watery current 

 speeding over the land and leaving a train of debris behind it on 

 meeting with an obstacle. 



All the facts, therefore, seem to concur in claiming as the efficient 

 cause of the Swedish asar gi'eat masses of water, sometimes rushing 

 in a series of more or less parallel currents, colliding and elbowing 

 each other and dropping their burden along their edges, and 

 sometimes coalescing into a more or less continuous flood. The 

 abnormal size, the great length and height, and the portentous 

 masses of materials comprised in these mounds, and especially the 

 great size of their contained boulders, necessitate our postulating 

 that the rush of waters must have been on a corresponding scale. 



There still remains the question as to whether the asar were the 

 result of the diurnal (tidal) operations of a turbulent ocean or the rapid 

 and sudden action of a great and cataclysmic rush of water, such as 

 we have on other grounds postulated. In regard to this question, 

 they present some features which seem to me to be conclusive. 



In the first place, if they had been the result of the diurnal action 

 of the sea, their internal structure would have been uniform. 

 Instead of this we find that, while the great mass of the materials in 

 most of them is arranged in heterogeneous fashion, being formed 

 of a medley of different- sized boulders, their upper layers consist 

 of stratified sands, finely levigated and laminated clays and brick- 

 earths, mixed with light shells, or they are formed entirely of 

 sands marked by violent cross-bedding, pointing very clearly to 

 a great flood which threw down the great mass of its burden 

 regardless of its gravity, and ended up, as floods always do, by 

 depositing over the previous load the finer contents which it held in 

 suspension in laminae and layers. The very fact of the great mass 

 of the substance of the coarse asar being heterooeneous and 



