NA TURE 



[July 5, 1906 



south, it will probably be found that few towns and 

 villages have escaped some injury. The isoseismal 

 line of intensity 8, or the curve which bounds the 

 area of slight damage to buildings, seems to be 

 roughly elliptical in form, about twenty-eight miles 

 from east to west and eighteen to tweritv miles 

 from north to south, or a little more than too square 

 miles in area. 



Nearly all the strongest British earthquakes belong 

 to the class which have been called " twin " earth- 

 quakes. Tliey originate within two foci, which are 

 nearly or quite detached, with their centres, as a rule, 

 about eight or ten miles apart. But the chief 

 peculiarity about them is that the two impulses which 

 cans™ them take place almost simultaneously, or, if 

 not quite so, that the second impulse occurs before 

 the vibrations from the first focus have time to reach 

 the other, the two impulses being thus due to a single 

 generative effort. 



From the descriptions which have been given there 

 can, I think, be no doubt that the recent shock was 

 a typical twin earthquake. Many hundreds of observ- 

 ations will be required to determine the positions of 

 tlie twin foci, and to ascertain which focus was first 

 in action. But, so far as the evidence already collected 

 allows us to judge, the foci appear to have been 

 situated along a nearly east and west line, and are 

 probably coincident with an east and west fault, pass- 

 ing close to Llanelly, Swansea, and Neath. It would 

 be useless at present to attempt a more exact definition 

 of the originating fault, but it is clearly connected 

 with the great Armorican svstem of crust-movements, 

 which attain their maximum in Brittany and mid- 

 Devon, and, as thev enter South Wales, begin to die 

 away. In this district, as Mr. Aubrey Strahan re- 

 marked in his address at the Cambridge meeting of 

 the British Association, the chief disturbances are of 

 post-Carboniferous age. That they are still occasion- 

 ally continued, though on a much smaller scale, the 

 recent shock bears ample testimony. 



It is evident from the above account that the earth- 

 quake presents several features of considerable interest 

 to geologists. The district is also one that affords 

 unusual opportunities for the study of the nature and 

 effects of the shock in deep mines, and it is to be 

 hoped that our somewhat scantv knowledge will be 

 advanced in this respect. 



I take this opportunity of stating how greatly mv 

 investigation of the earthquake would be assisted bv 

 the contribution of records from different places and 

 especially from 'the workings in the mining districts 

 The pointson which I wish to obtain information will 

 be found in many local newspapers, but I shall be 

 glad to send forms on which descriptions may be 

 conveniently entered if application is made to me at 

 i6 Manor Road, Edgbaston, Birmingham. 



Charles Davison. 



PROFS. N. S. SHALER AND I. C. RUSSELL. 

 /"^EOLOGICAL science, and America in particular, 

 ^-^ has suffered a severe loss in the deaths of two 

 university professors, N. S. Shaler, of Harvard, and 

 I. C. Russell, of Michigan. 



Prof. Nathaniel Southgate Shaler, who was born 

 in Newport, Kentucky, on Februarv 20, 1841, 

 graduated at Harvard University, and served two 

 years as an artillery officer in the Union Army during 

 the Civil War. Subsequently he pursued the study 

 of natural science, to which he had been attracted at 

 the Lawrence Scientific School in Cambridge, took 

 the degree of Sc.D. in 1S65, and became in 1868 

 instructor in zoology and geo'logy in that school, and 



NO. I 9 14, VOL. 74] 



also professor of palaeontology in Harvard University. 

 While retaining this professorship, he was in 1873 

 appointed director of the second Kentucky Geological 

 Survey, a post he held until 1880; and in 18S7 he 

 became professor of geology in Harvard University, 

 and occupied the chair until his death this year at 

 the age of sixty-five. When little more than twenty 

 years of age he discussed the age of the rocks in 

 .^nticosti, in a paper read before the Boston Society 

 of Natural History, and in 1865 and following years 

 he brought before the same society his views on the 

 elevation of continental masses, arguing that sea- 

 bottoms on which sedimentation was taking place 

 were areas of depression, and that prominent lands 

 undergoing denudation were areas of uplift. He dis- 

 cussed the formation of mountain chains (1866), and 

 maintained that while the continental folds were 

 corrugations of the mass of the earth's crust, the 

 mountain chains were folds only of the outer portion 

 of the crust caused by contraction of its underlvin.g 

 part, and that the formation of mountain chains 

 would be promoted by the subsidence of the ocean's 

 floors, fractures and dislocations being thereby pro- 

 duced along their borders (see G. P. Merrill's " Con- 

 tributions to the History of American Geology," 

 1906). In a subsequent paper (1875) Shaler suggested 

 that the transfer of weight to the land bv the accumu- 

 lation of an ice-sheet would influence terrestrial move- 

 ments. He also discussed the possibility of the Japan 

 current flowing at the close of the Glacial period over 

 what is now land about Bering's Strait, and thus 

 modifying the climatic conditions. He issued memoirs 

 and reports on the geology of Kentucky (1876, &c.), 

 and in later years dealt with a great variety of sub- 

 jects, scientific and practical, including the classifi- 

 cation of lavas, the fossil brachiopods of the Ohio 

 valley, soils, the geological history of harbours, peat- 

 deposits, road-stones, the features of the earth and 

 moon, &c. He was author of important reports on 

 the geology of Cape Cod district (i8g8); (with J. B. 

 Wood worth) geolog)' of the Richmond Basin, Vir- 

 ginia (i8qg); and (with A. F. Foerste) geology of the 

 Narragansett Basin (i8gq). He wrote also " Outlines 

 of the Earth's History" (i8q8); "Sea and Land: 

 Features of Coasts and Oceans, with Special Refer- 

 ence to the Life of Man" (1895); "Study of Life 

 and Death " (igoo), and other works of a more or 

 less popular character. 



Prof. Israel Cook Russell, whose death occurred at 

 the age of fifty-three, was born at Garrattsville, in 

 New York State, on December 10, 1852. He gradu- 

 ated at the L^niversitv of New York in 1872, and after 

 further study at the .School of Mines, Columbia, 

 was appointed a member of the L^S. expedition to 

 New Zealand (1874-5) fo observe the transit of Venus. 

 His attention, however, was given mainly to the study 

 of physical geology. On his return from New Zealand 

 he became assistant professor of geology at the 

 Columbia School of Mines, and in 1878 was appointed 

 assistant geologist on the V.S. geographical and 

 ecological survey west of the one hundredth meridian. 

 From 1880 to 1892 he served as geologist on the LT.S. 

 Geological Survey, and in 1892 he became professor 

 of geology in the L'niversity of Michigan. His earlier 

 papers (1878) dealt with the physical history of the 

 Trias in New Jersey, and with the intrusive nature 

 of the eruptive rocks, in which he recorded the 

 presence of a .solid hydrocarbon. One of his more 

 important works w-as a sketch of the geological 

 history of the former Lake Lahontan, which in 

 Quaternary times occupied an area of nearly 8500 

 square miles in N.W. Nevada (188-5); he wrote also 

 on the glaciers of Mount Rainier (1898), and on the 

 geology- of the Cascade Mountains (1900). Of later 



