260 Scientific Intelligence. 



the fact that successive earthquakes occurred repeatedly along 

 a line marking the position of a fault. The latest epoch in seis- 

 mology was inaugurated in 1894, when the possibility of record- 

 ing distant earthquakes was made known. Since that date the 

 British Association and the Vienna Academy of Sciences, the 

 Japanese Earthquake Investigation Committee, and, finally, the 

 Committee on Seismology for the American Association, have 

 taken up the work and have carried it so far as to show that the 

 chief cause of earthquakes is faulting and that the ultimate 

 cause is only approximately known. Statistical study has shown 

 that earthquakes are distributed along Tertiary mountain sys- 

 tems, in zones bordering the coasts, in regions of active vulcanism, 

 and in the most mobile portions of the earth's crust. Professor 

 Hobbs discusses the nature of earthquake fissures and earthquake 

 shocks, and contributes important new material regarding the 

 derangement of surface waters and ground waters, including the 

 origin and behavior of certain cold and thermal springs and, in 

 this same connection, discusses the origin of sand dikes and the 

 peculiar sandstone "pipes "of Wales and other districts. Full 

 descriptions are given of the following earthquakes : Lisbon, 

 1755, Calabria, 1783, the Mino-Owari, 1891, Iceland, 1896, 

 Assam, 1897, Kingston, 1907. The chief earthquakes in the 

 United States, namely, the New Madrid, 1811, Owens Valley, 

 1872, Charleston, 1886, Sonora, 1887, Yakutat Bay, 1899, San 

 Francisco, 1906, are discussed somewhat fully. 



The particular contribution of Professor Hobbs to seismology 

 is the location of earth " lineaments " by topographic methods 

 and the connection of earthquakes with these supposed " linea- 

 ments." The line of reasoning followed here departs widely 

 from the safe ground of theory based on fact. In some cases 

 fault lines appear to be located by Professor Hobbs not as the 

 result of field evidence, but because earthquakes have occurred 

 in certain localities, which places may be connected by straight 

 lines. This leads to the assumption that faults exist and are 

 responsible for the topography in regions where other explana- 

 tions are as acceptable. For instance, East Haddam, Conn., is 

 given first rank in seismicity for the entire eastern United States 

 and is said to be " located " where the fall line intersects the 

 gorge of the lower Connecticut, itself a strongly marked linea- 

 ment." The objections to these statements are, first, that the 

 fall line, as physiographers understand it, does not extend 

 through East Haddam, and, secondly, there is no proof that the 

 lower Connecticut follows a fall line. If the location of other 

 earth " lineaments " rest on no better geologic data than is shown 

 by this instance, the conclusion of Professor Hobbs must be con- 

 sidered speculative. 



Aside from its theoretical portions this book is a valuable gen- 

 eral discussion of earthquakes, and students will be particularly 

 thankful for the chapters discussing the methods of study of 

 earthquakes in the field and the efficiency of different types of 



