1847.] Association of Geologists and JVaturalists. 2 13 



A report was read from Mr. Vanuxera, on the Taconic system, 

 to show that there are locks intermediate between the primary 

 rocks and the Potsdam sandstone. 



Mr. S. S. Haldeman read a report, showing that Mtops Trilin-' 

 eatus and Triarthus Beckii are not identicaL 



Evening Session — Friday, Sept. 24. 



Mr. Hodge made some remarks on the economic geology of 

 the Berkshire % alley. He exhibited some very fine, pure, and 

 white sand, for the manufacture of glass, obtained there in vast 

 quantities, and at very little expense. He exhibited a beautiful 

 glass vase made from it. He believed we should soon be able to 

 make the best of plate glass. 



On the Phenomena of Drift and Glacial Action in JVeiv England, 

 by Mr. Desor. 



There are four forms of drift. The first consists of coarse 

 stones, imbedded in loam, as on the shores of New England and 

 New York: this has no stratification. It contains not a ii^w fos- 

 sils; most of these stones are scratched. The city of Boston is 

 built on this formation, and the islands of its harbor consist of it. 

 The next is the clay formation, which is called tertiary, or pleis- 

 tocene clay; this is the true drift, and contains many fossils. This 

 is found in the lower parts and depressions, and may be seen in 

 almost all the railroad cuts in the valleys. It is stratified; the 

 fossils preserve their color, the calcareous parts being destroyed, 

 while the animal parts are not. Over this clay bed is a bed of 

 sand, between which and the clay, or just at the top of the clay, 

 the fossils are found. The ridges (the moraines of Prof Hitch- 

 cock,) are hills on the surface of the clay, or sand. They some- 

 times extend for miles, and form natural roads in many countries, 

 as in Sweden. Many consider them submarine beaches. There 

 is a good instance at Andover, Mass. The boulders have two 

 kinds of distribution — one on the top of these ridges, and one 

 general. These four forms are not all found together. 



The whole surface of New England is scratched; this is the 

 rule, not the exception, the summit of Mt. Washington is the only 

 spot in New" England which is not thus scratched. 



These same phenomena of the drift occur in Scandinavia. They 

 each correspond to a peculiar era of the earth's surface. 



From the examination of these scratches and polishings, we 

 may say that there has been a subsidence, and afterwards a gra- 

 dual emergence of this whole hemisphere. The same shells are 

 found on the heights of Montreal, and at Augusta, Maine, four 

 hundred and thirty feet below it; they were first deposited at 



