174 Association of American Geologists. 



Dr. Jackson stated that the mass of infusorial deposit found 

 under peat bogs is hydrate of sihca, which loses by being heated 

 to redness from 12 to 15 per cent., principally vegetable matter. 

 Great abundance of this material occurs at Newfield, in Maine, 

 where it covers many hundred acres, and is live or six feet thick. 

 After burning, it is so white and beautiful that it has been fraud- 

 ulently sold for magnesia alba. The ammonia which is evolved 

 in its destructive distillation, is probably derived from the crenic 

 and apocrenic acids which it contains. Phosphate of lime and 

 manganese are found in it in small quantities. As a fertilizer of 

 land, it is considered of use when containing in large quantity 

 the juices of plants. 



A memoir from M. Alexandre Yatteraare was presented, pro- 

 posing a general system of exchange of objects of nature and 

 art among all nations. It was by motion laid on the table. 



The subject of bowlders and diluvial scratches was then 

 brought up for discussion by Prof. Mather, and a protracted de- 

 bate ensued, in which many of the members joined. 



Prof. Mather inferred from the facts in the case, that the 

 bowlders and diluvial scratches had, in general, come from the 

 north ; those on the east of the Hudson from the northwest, 

 those on the west from the northeast, as by the result of two 

 forces. 



The diluvial furrows are, in general, parallel to the valleys in 

 which they are found — thus in the small transverse valleys, the 

 scratches are found parallel to the direction of the valleys— and 

 not coincident with those of the main valleys. All the bowl- 

 ders seem to have been brought from the northwest, both at the 

 east and beyond the river St. Peter's at the west, and very few 

 are found below 38° or 39° of north latitude. 



The chairman {Prof Silliman) cited the recorded observa- 

 tions of Mr. C. Darwin, naturalist to H. M. ship Beagle, that in 

 South America no bowlders occur nearer the equator than about 

 40° south latitude. 



Prof Mather had not seen any bowlders in the coal region of 

 Ohio, and very few in Kentucky. He thought that the bowl- 

 ders mentioned by Mr. Hodge in the gold region of North Caro- 

 lina, were not transported masses, but were composed of granite 

 which had suffered decomposition in situ by atmospheric agency. 



