224 SCIENTIFIC RECORD FOR 1884. 



240 miles; to False Point, 180 miles ; aud to Diiblat, at the mouth of the 

 Hooghly, 120 miles. The average depth of the sea is kiiowu to dimin- 

 ish iu every instance of diminished velocity, and in all these cases the 

 crest of a positive wave preceded the trough or negative wave. 



At the Minneapolis meeting of the American Association for the Ad- 

 vancement of Science [Proc.A. A. A. S., 1883, xxxii, 253), Richard Owen 

 discussed the grand lines of orographic development of the continental 

 masses, and their relations to volcanic and seismic regions. He showed 

 that a series of mountain chains, in several parallel ranges, extends 

 nearly east and west from the land center in Switzerland to the equator 

 at Quito and Sumatra, and that active volcanoes are often found in 

 this stony girdle, while seismic activity is more often displayed within 

 areas inclosed by the great orographic links of this chain. 



G. K. Gilbert offers {Am. Jour. ISci., xxvii, 49) a theory to account 

 for the earthquakes of the Great Basin. The elevation of mountain 

 chains being gradual, results in a slowly increasing strain upon the ad- 

 jacent strata, which strain is from time to time relieved by the forma- 

 tion of faults at the foot of the range. This fault formation constitutes 

 an earthquake shock; and the tension of the strata having been thus 

 relieved, a longer or shorter period of quiescence will follow, until the 

 tension again accumulates to the point of fracture. Applying these 

 principles to the particular case, it is noted that fault scarps are found 

 along the western base of the Wasatch Range aud along the eastern 

 base of the Sierra Nevada, one of the latter having been formed by 

 the Owens Valley earthquake, which caused so much damage in 1872. 

 But the fault scarp of the Wasatch is notably interrupted from Warm 

 Springs to Emigration Canon, near Salt Lake City, whence the infer- 

 ence is drawn that the strain of the rising mountains has not there been 

 relieved in recent time, and consequently the inhabitants of that city 

 may anticipate the occurrence of an earthquake shock to relieve this 

 tension, which will be more severe the longer it is delayed. 



In the first part of Das Antlitz der Erde (Leipzig, 1883) Edward 

 Suess has discussed, in connection with other matters, both earthquakes 

 and volcanoes. Having iu the second chapter described several regions 

 which are subject to earthquakes, as the Northeastern Alps, Southern 

 Italy, Central America, and the west coast of South America, in the 

 third chapter he discusses the general topic of dislocations and the 

 strains which cause them, and in the fifth the different classes of earth- 

 quakes and their relation to more extensive movements of the crust. 

 The fourth chapter is devoted to volcanoes, tracing the different stages 

 in the life history of an eruptive mountain, as illustrated in the i)henom- 

 ena of the present day, from those which have broken forth within 

 historical time and are still continuously active, through the succession 

 of less and less active cones, to those which have not only been long 

 extinct, but have been reduced to ruins by the processes of erosion, and 

 finally to those masses of eruptive matter which never reached the sur- 



