PLEISTOCENE GEOLOGY OP MOOERS QUADRANGLE 



15 



Alder Bend deposit 

 Along the banks of the Big Chazy river, from half a mile to a 

 mile above Alder Bend, there is a deposit of gravel and sand 

 mainly developed on the western bank of the stream. This ap- 

 pears to have been made in a temporary lake whose surface 

 approximately coincided with the 1080 foot contour line, but no 

 other evidence demanding such a lake for its explanation has 

 been observed. 



Deer brook deposit 

 On the north branch of the Big Chazy river northwest of Irona, 

 there is a noticeable area of sands often fine, which is evidently 

 the remains of a delta made on that stream. The deposit has 

 suffered some dissection. The tops of the remnants lie between 

 the GOO foot and 700 foot contour lines and indicate a local water 

 level somewhere between these bights. No definite margin was 

 detected in this deposit to indicate whether it was built up against 

 the ice margin or under the free conditions of open water. The 

 fineness of the sand toward the eastern extension of the deposit 

 favors the latter supposition. 



Altona deposit 



A smaller delta than the preceding constitutes the flat ground 

 on which a good part of the village of Altona is built. This 

 deposit is decidedly gravelly south of the railroad. Just north 

 of the railroad and west of the station, there is a deposit of fine 

 sand, probably the lobate, free margin of the delta. All the cir- 

 cumstances here point to the building of the deposit in a body 

 of water whose level corresponded with the 640 foot contour line, 

 traces of which in the form of beaches occur to the east of Altona 

 village. It is probable that the delta above described on the north 

 branch of the Big Chazy was deposited earlier than this one in 

 a higher water stage. The Altona delta appears to have been 

 built by the Big Chazy before it had excavated its present course 

 to the east of the village. 



Deposits of gravel and sand in the form of deltas occur at lower 

 levels, but they are so clearly associated with the marine invasion 

 of the district that reference to them is deferred to a later page. 



