CONSOLIDATED GLACIAL DEPOSITS 6oi 



the lobate front is the slope of the front of the original delta where 

 the oblique frontal layers or fore-set beds were added. The loba- 

 tion is due to the division of the stream into a number of spreading 

 fingers or distributaries, each of which builds its own portion of the 

 delta forward. In section it will be seen that the greatest part of 

 the sand plain is composed of the sloping fore-set beds, which are 

 inclined at an angle of 20 or more degrees. The upper ends of 

 the fore-set beds are abruptly truncated, and on these truncated 

 edges rest the coarser, nearly horizontal, top-set beds which con- 

 stitute the subaerial part of the delta. The foot of the fore-set 

 beds generally rests upon a thin series of bottom-set beds of finest 

 material, often of clay or rock flour. All the beds are well stratified 

 and the pebbles are, as a rule, well rounded. 



Consolidated Sand Plains. Sand plains of Pleistocenic age have, 

 in some cases, become consolidated so as to form a rock mass of 

 more or less induration. This is especially the case where many of 

 the pebbles are of limestone, when partial solution and redeposition 

 of the lime in the interstices will occur. A typical example of 

 such a consolidated deposit is seen on the banks of the lower 

 Niagara River, near the railroad station at Lewiston, New York. 

 Here steep fore-set beds are seen dipping at an average angle of 

 15-20 degrees toward the south. The beds are sufficiently well 

 cemented to form a vertical wall, though the material can be broken 

 into its component pebbles by blows of a hammer. The deposit, 

 which is perhaps 30 or 40 feet thick, appears to have formed in a 

 body of water held up against the front of the Niagara escarpment 

 by an ice lobe lying a short distance to the north. Streams from 

 this ice lobe supplied the pebbles and sand which built up the delta. 



This deposit is sufficiently consolidated to resist ordinary erosion, 

 and river, lacustrine, or even marine sediments could be formed over 

 it without disturbing it. Indeed, since the formation of this deposit 

 this region is believed to have been invaded by the sea by way of the 

 Hudson, Lake Champlain, and the St. Lawrence, but this was not 

 of sufficient duration to permit the formation of extensive marine 

 deposits. It is easy to see, however, that these steeply inclined 

 delta beds of coarse material, followed by marine sediments, such 

 as would have been formed had the sea stood here longer, and this 

 in turn by lacustrine deposits, such as would be formed if the 

 present lake should expand, would give a complex succession of 

 formations, the history of which would be decipherable only with 

 considerable difficulty. 



The NageWuli of Sakburg. (Crammer-13 :J^5-J5^.) The city 

 of Salzburg in the Austrian province of the same name and close 



