74 EEPORT OF THE SECRETARY. 



assistauts, lie himself having been principally engaged in the prepara- 

 tion of material for publication. Such field work as w as done under his 

 direction was mainly in the Gunnison or Crested Butte region and in the 

 Denver Basin region. His assistants, Messrs. Cross and Eldridge. made 

 large collections of specimens, and the former, in the course of his work, 

 made a nuipber of important contributions to petrography. 



California Division of Geology. — Eesuming his field studies of the ge- 

 ology of the quicksilver deposits of the Pacific slope, Mr. G. F. Becker 

 brought his investigation to a conclusion, and devoted himself to the 

 preparation of a monograph on the results. This monograph is now in 

 an advanced state, and will soon be placed in the hands of the printer. 

 In his observation of the stratigraphy of California Mr. Becker was led 

 to consider a number of the physical and chemical questions involved, 

 and his work upon these resulted in the disclosure of certain novel laws 

 of mechanics and physics that are believed to have a high value. Tlius, 

 in considering the fundamental shape of volcanic cones, Mr. Becker 

 found that the form of such cones could be determined mathematically 

 with all possible definiteness, and that this form coincides in the most 

 remarkable way with iihotographs of actual volcanic cones in America 

 and Japan. A contribution to the general law of mechanics which grew 

 out of his investigation of quicksilver is called a theorem of maximum 

 dissipativity, according to which there is in every system a tendency to 

 motions of a shorter period, this tendency being the greatest possible 

 when the motions of the system have periods which differ considerably. 



Division of Volcanic Geology. — Captain C. E. Button, with his assistant, 

 Mr. J. S. Diller, devoted his field work to a study of the Cascade Range 

 and its geological relation to the Coast Eanges. The belt of country be- 

 tween the shore of the Pacific and the Cascade Eange he finds to bo 

 occupied by mountains which do not group themselves into distinct 

 ranges, but which are crowded closely together and present forms alto- 

 gether jieculiar by reason of their irregularity, want of definite trend, 

 and absence of anything approaching structural axes. The attitudes 

 of the older rocks in this region disclose a scene of stratigraphic confu- 

 sion, displacement, and distortion without a parallel in his experience. 

 The most striking feature of the Cascade Eange is undoubtedly Crater 

 Lake, of which Captain Button made a thorough examination. The 

 occurrence of several notable earthquake tremors in the Atlantic States 

 in the summer and autumn of 1884, and the fact that such disturbances 

 are more numerous than is generally supposed, led to some preliminary 

 measures under the direction of Captain Button looking to the estab- 

 lishment of systematic observations of such phenomena. A consulta- 

 tion was held between several members of the Geological Survey corps 

 and Prof. C. G. Eockwood, of Princeton, Mr. W. M. Bavis, of Harvard, 

 Prof. Cleveland Abbe, of the Signal Service, and Mr. H. M. Paul, of 



