REPORT OF EXECUTIVE COMMITTEE. II9 



GEOPHYSICS. 



Frank D. Adams, McGill University, Montreal, Canada. Grant 

 No. 117. For i7ivestigation on flow of rocks. (For first report 

 see Year Book No. 2, p. xxxiv. ) $1,500. 



Abstract of Report. — The experimental work carried on during the 

 past year was commenced by an investigation into the plasticity of a 

 series of minerals, including a number of the chief rock-making con- 

 stituents. These were for the most part the minerals constituting 

 Mohs' scale of hardness. In this work the method suggested many 

 years ago by Professor Kick was employed, which consists of submit- 

 ting the material to differential pressure obtained by embedding the 

 specimen in alum or sulphur, inclosing the whole in a stout copper 

 box, and then slowly deforming it in a powerful press. 



It was found that under these conditions rock salt, selenite. Ice 

 land spar, and fluorite could be readily deformed. The next higher 

 mineral on the scale of hardness — namely, apatite — also showed 

 distinct evidence of plasticity, although this was much less marked 

 than in the case of the minerals already mentioned. Diopside, when 

 treated in this way, developed a most remarkably perfect twinning 

 parallel to the base. This twinning is often seen in this species when 

 it is found in the ancient crystalline schists, but has never formerly 

 been produced in anything like the same perfection as in these ex- 

 periments. The harder minerals (pyrite, garnet, and quartz) showed 

 no plastic deformation, but were crushed to powder under the 

 conditions of the experiment. 



The flow of marble was then made the subject of further investi- 

 gation, the experimental conditions being varied and the rock being 

 subjected to much higher pressure than in former trials. One inter- 

 esting result attained in this connection was the complete plastic 

 deformation of this rock at ordinary temperatures, the constituent 

 grains of calcite moving on their gliding planes without the develop- 

 ment of any breaking or granulation. In former experiments this 

 had only been accomplished when the rock was deformed at a 

 temperature of at least 300° C. 



The investigations were then extended to a series of impure lime- 

 stones, presenting a great variety in character, some of them con- 

 taining a large amount of clay, some highly arenaceous, and some 

 bituminous. These were deformed in heavy tubes of nickel steel, 

 both at ordinary temperatures and when heated to 300° or 400° C. 



Experiments were also carried on with several typical dolomites, 

 and it was found that while these could be made to flow, they did so 

 much less readily than ordinary limestones. 



