Geological iSocieh/ a ml A. A. A.S. Jfeef/Hf/s. — I'p/ttnii. 247 
■days of a single week, instead of being interrupted, as hereto- 
fore, by the excursions of Saturday and the rest of Sunday. 
Eighteen papers were read in Section E, as follows: 
The Relations of Primary and Secondari/ Structures in Rocks. C. R. 
Van Hise, Madison, Wis. Cleavage was distinguished from fissility. 
A slate or a schist may have both, and they may be parallel or inclined 
to each other. The metamorphosed rocks have secondary structure 
imposed upon them, whose lamination rarely correspond^ with the bed- 
ding. The difficulties of determining the true thickness of such Vjeds 
is great, and highly exaggerated estimates have often been made in sec- 
tions of the ancient crystalline rocks. 
The ArcJuean and Cambrian rocks of the Green Mountain Range in 
southern Massachusetis. B. K. Emerson, Amherst, Mass. The main 
purpose of the paper was to bring to the notice of the audience a man- 
uscript geological map of the south central jjortion of Massachusetts 
fi-om the Hovisatonic valley to the eastern border of Worcester county. 
The author described in some detail several typical outcrops of pre- 
Cambrian rocks which lie along the western rim of the Green Mountain 
belt as it crosses Massachusetts. 
The Hinsdale area was described as one where the pre-Cambrian rocks 
occur in crescentic bands. The oldest rock is the Hinsdale gneiss in the 
center, and this is surrounded by the coarse Hinsdale limestone, the 
Lee gneiss, and the Washington gneiss, in succession. It was shown 
how the unequal wear of the j^re-Cambrian formations had produced 
the uppcn- part of the Westford river pass. 
The Tyringham area was described as giving evidence of an old pre- 
Cambrian land with east to west folds beneath the north to south Green 
Mountain folds. Erosion of pre-Cambrian limestones has formed the 
deep East Lee valley and the basins of many small lakes. In the Bear 
Mountain-Monterey system of V-shaped overturned anticlines, each fold 
of a numerous parallel series is bent sharply, so that the front bed may 
be compared to the double concave surface of a railroad snow-plow. 
Tracts of crystalline rocks east of the foregoing, with prevailing north 
to south trend, were briefly characterized, beginning with the pre-Cam- 
brian rocks and ending with the Uxjper Devonian crystallines of Bern- 
ardston. Attempts are being made toward a correlation of the crystal- 
lines east of the Connecticut river with those on the west. The schists 
of Worcester county, with their abundant granites, were also described, 
with indication of their relations to the f)robable pre-Cambrian area of 
Sutton and Douglas in the southeastern part of this county. The 
opinion was expressed that probably some of the granites on lioth sides 
of the Connecticut river are of Carboniferous age. 
One interesting sjjecial point was the descrijjtion of the stretched 
quartz pebbles in the conglomerate gneisses at Woonsocket, R. I., and 
elsewhere. Their present dimensions in some cases are 18 by 4 l)y '1 
inches. 
