290 THE GLACIAL LAKE AGASSIZ. 



south aim iu)rtli. Next eastward rises a moderately iiudulating slope of till, 

 strewn with abundant bowlders; and rarely a bowlder 2 to 5 feet in diam- 

 eter is seen on the spriug^y land that marks the border of the ancient lake. 



DELTA OF THE BUFFALO EIVER. 



(plate XXV.) 



The delta brought into the east side of Lake Agassiz bv the Buffalo 

 River extends about 5 miles southwestward from ]\lusk()d;i, forming a con- 

 tinuously descending plain of stratified sand and tine gravel, declining from 

 1,100 feet near Muskoda to 1,073 feet at its southwestern limit in the north 

 part of section 34, Riverton. Here and northward along a distance of 3 

 miles to the Buftalo River this delta plain is terminate<l by a steep slope, 

 25 to 40 feet high, like the face of a terrace. The outer portion of the 

 original delta, beyond this line, has been carried away Ijy the waves and 

 shore currents of the lake when it stood at the lower levels marked b}' the 

 iNorcross and Tiutah beaches, as shown in fig. 11. 



Fig. 11. — Section across the delta of the Eutialo lliver. Horizoutal acaltf, oue.halt iiiilo tu an inch. 



Northern Paciiic Railroad track at ]\Iuskoda, 1,000 feet. Threshold 

 of church a quarter of a mile southeast from Muskoda depot, 1,113 feet. 

 Beach here and for a third of a mile south to the Buffalo River, as also at 

 the excavation for the railroad, 25 rods north of the church, nearly uniform 

 elevation of its crest, 1,113 to 1,114 feet. The beach is 35 rods wide, rising 

 14 or 15 feet in a gentle swell above the edge of the delta of modified drift 

 on the west and descending the same amount t() the depression at its east 

 side. It is made up of interstratified gravel and sand, the former prevail- 

 ing, including pebbles up to 3 or 4 inches and rarely 6 or even 9 inches in 

 diameter, all waterworn. Half or two-thii'ds of these pebbles and cobbles 

 are limestone. No bowlders occur here, nor are they found in any of the 

 beach deposits of Lake Agassiz. 



