282 



SCIENCE. 



[N. S. TOL. 11. No. 36. 



A list of localities of the titaniferons ores 

 was given and the distinction was made be- 

 tween the smaller bodies which are, so far 

 as can be seen, basic developments of gab- 

 bro, and the enormous ore bodies at the old 

 Adirondack Iron Woi'ks, in the heart of 

 the mountains. These latter are in massive 

 anorthosite, which is almost entirelj^ formed 

 of large, blue-black crystals of labradorite. 

 The ore bodies, and especially the one 

 crossing Lake Sanford, contain numerous 

 included labradorite crj'stals, each of which 

 is surrounded by a reaction rim 5-10 mm. 

 across. It was further shown that the wall 

 rocks show no signs of the widespread 

 crushing that is exhibited in the general 

 ' mortar-structure ' of the Adirondack and 

 Canadian anorthosites, but are plutonic 

 rocks free from evidences of dynamic met- 

 amorphism. The argument is then made 

 that the ores are segregations from an ig- 

 neous magma formed during the process of 

 cooling and crystallization. In conclusion 

 the speaker gave some notes on recent at- 

 tempts to utilize these ores that bid fair to 

 be successful. 



In discussion, C. E. Van Hise mentioned 

 the similar bodies of titaniferons ores in the 

 gabbros of Lake Superior, adding, however, 

 that there had been some infiltration of iron 

 oxide since the formation. 



The last paper of the meeting was pre- 

 sented by J. C. Branner, of Stanford Uni- 

 versity, California, on ' The Decomposition 

 of Eocks in Brazil.' 



The decomposition of rocks is much more 

 profound in Brazil than in temperate re- 

 gions. This decay has lately been demon- 

 strated by railway cuts and tunnels and by 

 deep mines, records of which was given. 

 This decomposition is produced by mechan- 

 ical and chemical agencies. 



The chief mechanical agency is daily 

 change of temperature sufiFered by rocks 

 openly exposed to the sun — about 100 de- 

 grees Far. This causes exfoliation of moun- 



tain masses and of boulders and open crev- 

 ices that admit water, air, insects, and these 

 set ujj a train of reactions that soon destroy 

 the rock. Chemical agencies are organic 

 and inorganic. The inorganic agencies are 

 carbonic and nitric acid brought down in 

 rains in great quantities. The organic 

 chemical agencies are insects and plants. 

 The ground is then filled with vast hordes 

 of ants whose breath and food form acids 

 that attack the rocks. The rapid decaj'' of 

 a very rank vegetation contributes the chief 

 agent of rock decomposition. Rain falling 

 on hot rocks greatly increases the action of 

 these agents. The paper was illustrated by 

 sketches and photographs and excited the 

 deepest interest. 



On account of the absence of the authors 

 and the need of adjournment in view of an 

 excursion that was offered by Professor 

 Emerson to Mt. Holyoke in the afternoon, 

 the following papers were only read or an- 

 nounced by title : 



George M. Dawson and E. G. McConnell: 

 ' On the Glacial Deposit^ of Southwestern 

 Alberta,' in the vicinitj' of the Rocky 

 Mountains. Warren Upham: ' Drumlins 

 and Marginal Moraines of Ice-sheets.' N". 

 H. Darton: 'Notes on Relations of Lower 

 Members of Coastal Plain Series in South 

 Carolina.' N. H. Darton: ' Resum6 of 

 General Stratigraphic Relations in the 

 Atlantic Coastal Plain from New Jersey 

 to South Carolina.' George P. Merrill: 

 ' On Asbestos and Asbestiform Minerals.' 

 C. A. Gordon: Syenite-Gneiss (Leopard 

 Eock) from the Apatite Eegion of Ottawa 

 County, Canada. 



The regular meeting adjourned after pass- 

 ing a vote of thanks to the Librarj' Associ- 

 ation of Spring-field, and to the Local Com- 

 mittee. 



In the afternoon thirty-seven fellows ac- 

 companied Professor Emerson to Mt. Hol- 

 yoke to see the contacts of trap and sand- 

 stone, the dikes, plugs, bird-track and other 



