Pleistocene Pap€i\'< at tJieWasJiliK/ton ^reetni(i><. 235 
followed by a stage of greater elevation than now, with active 
erosion. 
Prof. E. W. HiLGARD, in discus.sion, described the cross-bed- 
ding or "flow and plunge structure of tlie Lafayette formation 
along the Mississippi valley, attributing it to fluvial instead of 
marine deposition. The size of its pebbles on the lower Missis- 
sippi indicates for the river during the Lafayette epoch a gradient 
which would place the northern portion of its basin probably 
3,000 feet higher than now. 
Prof. C. H. Hitchcock referred to the marine beds of Maine, 
the St. Lawrence, and lake Champlain, enclosing arctic species of 
shells, as proof of subsidence of that region while the climate of 
the Glacial period still lingered there. 
Mr. Upham regarded the Lafayette and Columbia formations 
as fluvial deposits spread upon the coastal plain during epochs of 
plateau-like high altitude, and correlated these formations re- 
spectively with the first and second great glacial epochs. Before 
each of these stages of continental elevation, the Piedmont and 
Appalachian regions had long lain at lower altitudes, and their 
surface was largely occupied by residual clays and 1)y alluvial 
sand and gravel. With the elevation of the region, increased 
rainfall and snowfall and resulting river floods sw^ept away these 
superficial materials from the mountain vallej's and spread them 
on the plain, where the streams expanded over broad areas with 
shallow and slackened currents. When soon the supply of ma- 
terial decreased, the streams cut deeply into this plain. The 
Indo-Gangetic plain, south of the Himalayas, was cited as an 
analogous fiuvial formation of vast extent and rising from the 
sea level to an altitude of more than 900 feet. 
A study of the fossil (trlfoinio o/' the Siloer Lake region, Ore- 
gon. By R. W. Shufeldt. Many bones of l)irds are found in 
the Equus beds of this district. About fifty species of l)irds are 
determined, of which fifteen or sixteen are extinct, the propor- 
tion being nearly the same as of the associated mammalia. 
Nearly all are water birds. ))ut the prairie hen was also al»undant. 
Among the extinct species are a fiamingo. a heron, a raven, and 
a blackbird. 
The highest old shore line on Moeiiinoc island. By V. W. Tav- 
LOR. Five well-marked beach ridges of gravel and sand are 
found on this island, adjoining the strait between lakes Huron 
