THE BUCHANAN GRAVELS OF CALVIN AND THE 
IOWAN VALLEY TRAINS. 
M. M. LEIGHTON. 
In the various geological reports of counties in the Iowan 
area and of counties through which pass drainage lines from 
the Iowa area, the Buchanan gravels are classified into two 
phases : the upland phase and the valley phase. This classifica- 
tion dates back to 1898, when the Report of the Geology of 
Buchanan County by the late Dr. Samuel Calvin was published 
by the Iowa Geological Survey. In this report he set forth the 
conception that the upland gravels were deposited while the 
valleys were filled with ice and that the gravels in the terraces 
along the present streams were laid down after the Kansan 
ice had retreated some distance. In both cases the gravels were 
regarded by Calvin gs Kansan outwash and he called them Bu- 
chanan gravels. 
During the recent investigations which were carried on under 
the joint auspices of the U. S. Geological Survey and the Iowa 
Geological Survey by Dr. Wm. C. Alden and the writer, it was 
found that the terrace gravels or the valley phase of Calvin ? s 
Buchanan gravels represent valley-train deposits from the 
Iowan ice, and that they are therefore much younger than the 
highly decayed ferruginous gravels which are exposed in Cal- 
vin’s type out, the Doris pit of Buchanan county. This is es- 
tablished both by their differences in weathering and their dif- 
ferent relations to the Iowan drift. 
Department of Geology, 
University of Washington. 
