346 
The American Geologist. 
May, 1896 
Mr. T. W. Stanton reviewed in a similar manner the known inverte¬ 
brate life of the upper Cretaceous and Lower Eocene deposits of the 
Rocky Mountain region. The termination of true marine conditions 
was deemed to be the only safe criterion from this evidence to be applied 
in drawing a boundary for Mesozoic time. 
A comparison of the vertebrate faunas of the post-Laramie, Puerco, 
and Wasatch formations by Prof. W. B. Scott, of Princeton, was read 
by Mr. Cross. This brought out the remarkable differences in the 
vertebrate life of the three epochs and also the impossibility of explain¬ 
ing the abrupt changes in these faunas from our present knowledge of 
attendant conditions. 
Mr. F. V. Coville gave a review of the conditions affecting the dis¬ 
tribution and changes in living floras, starting with the great controlling 
factors, heat and moisture, and making suggestions as to the applica¬ 
bility of these data to geological history. 
Dr. C. Hart Merriam similarly described the conditions most effec¬ 
ting the distribution or causing modifications of terrestrial vertebrate 
life of the present, and discussed the apparent application of these facts 
to the past. 
Mr. Bailey Willis referred to the variable relations which might 
exist between angular unconformity and otherwise important strati¬ 
graphic breaks. 
Mr. R. T. Hill briefly referred to the development of knowledge of 
the lower Cretaceous series of Texas, to which he had given twenty years 
study, bringing out facts that bore in a general way on the subject under 
discussion. W. F. Morsell. 
Academy of Natural Sciences of Philadelphia. 
The mineralogical and geological section met on April 7th. 
Mr. Jos. Willcox described the process of obtaining quartz from the 
Oriskany sandstone of Pennsylvania to be used in the manufacture of 
glass. Mr. Keeley stated that the bed used for the purpose extends 
southward through Bedford county, where the material can be used 
without crushing, as it crumbles when exposed to the air. Prof. Carter 
suggested the use of the stone from the Conshohocken quarries as a 
source of silica. When treated with hydrochloric acid the stone yields 
flattened transparent grains of silica, not at all colored by iron. The 
percentage of mica is small, the glistening appearance of the rock being 
due to the presence of the quartz. 
Mr. Geo. Vaux, Jr., called attention to recent additions to the 
William A. Vaux collection which included superb crystals of calcite 
from the Joplin region, Missouri. They occur in caves opened for the 
working of lead and zinc. The several mines are characterized by dis¬ 
tinct forms of the mineral. The sphalerite, which is largely present, is 
being deposited at the present time, the handles of shovels and picks 
left in the mines being found covered with crystals. 
Mr. Theodore D. Rand described a fine collection of rocks from 
numerous localities in southeastern Pennsylvania. They belong to two 
groups, one bordering the ancient gneiss, the other and the more recent 
occurring in the mica schists and gneisses. The former are altered 
igneous rocks, either crysolitic of pyroxenic. The sources of the several 
forms were traced. 
Dr. F. Bascom reported that thin sections of the serpentine, from the 
belt in which the La Fayette and 41 Blue Rock” quarries are situated, 
showed that the rock was originally a peridotite. Olivine grains still 
remain, exhibiting the characteristic alteration, along a network of 
cracks, to serpentine. The alteration in many localities is carried far¬ 
ther, resulting in the formation of a perido-steatite. She also reported 
that the Conshohocken trap dike is a typical diabase, still compara¬ 
tively fresh and possessing both the constituents and structure of that 
rock-type. Edward J. Nolan, Rec. Sec’y. 
