216 The American Geologist. March, 1892 
Mr. C. W. Hall described the southeastern part of Minnesota. This 
region was first studied by D. D. Owen, 50 years ago, in his survey of the 
mineral lands of the Northwest. It contains rocks of Cambrian and $i- 
lurian date, with a small area of Devonian. ‘The Cambrian contains the 
Keweenawan and the great red quartzite of the Northwest and the Pots- 
dam sandstone, conglomeratic at base with pebbles of the same nature as 
the underlying rocks. After speaking at some length on the section as 
shown in Minnesota, the author mentioned the recent discovery of fos- 
sils in the St. Peter sandstone. Murchisonia, Endoceras, Helicotoma, 
etc., clearly indicate the Lower Silurian age of the sandstone. The beds 
below this are referred to the Cambrian, and include the two Magnesian 
groups of Owen. 
An illustrated evening lecture was delivered on Tuesday evening by 
Mr. I. C. Russell on his recent attempt to reach the top of Mt. St. Elias. 
A large map of Enchantment bay enabled the speaker to explain the 
topography, both terrestrial and glacial, of the region. Many points, 
especially of the latter, were of very great interest to glacial geologists, 
in consequence of their bearing on the problems of the glacial era. 
Great changes in the level of the land were shown to have occurred in 
very recent times. Glacial beds were seen lifted far above their original 
level, and the retreat of the ice, which apparently is still in progress 
over the region, has exposed areas but lately buried deep under the 
glacier. Special views of the ice-fields were shown by excellent photo- 
graphs on a screen. The deposits of morainic matter washed down 
from the glacier and deposited in the “glacial delta” showed large trees 
deeply buried, and, of course, dead. <A very striking feature in the land- 
scape is the great development of cryptogamic vegetation—mosses and 
ferns—forming a moist, soft cushion four or five feet deep, covering up 
fallen logs and unevenesses in the surface, andrendering progress slow, 
laborious aud fatiguing. The glacial features of the mountain, its rivers, 
ice-falls, crags and peaks, were vividly shown in a realistic manner, 
so that this little Known region was brought within almost familiar 
experience. 
On Wednesday morning the business of the session was resumed by 
the reading of a paper on the Valley of the Rio Grande in Texas, by Mr. 
Kk. T. Dumble, the state geologist. It contained a detailed account of 
the Cretaceous strata of that region and some of their fossils. 
Mr. W. H. Sherzer then read an elaborate revision of the rugose coral 
Chonophyllum, detailing its generic characters as regarded by himself, 
and maintaining that several species have hitherto been confounded 
under this name. He passed these in review, showing why they should 
be separated. Omphyma and Ptychophyllum were, he said, the forms 
with which it had been more frequently confused. 
Mr. C. Willard Hayes gave an account of the geology of the Yukon 
valley in Alaska. He reported immense deposits of volcanic material, 
fine sand, dust, pumice, sometimes covering the ground as snow, and a 
distinct and diagrammatic display of an overthrust fault half a mile in 
extent. Along the seacoast, in the neighborhood of Mt. St. Elias, occur 
