Januabt 29, 1909] 



SCIENCE 



199 



intruded into the beds. In some places this took 

 the form of dikes, such as the " stone wall " at 

 Raton; in other places it formed intrusive sheets 

 thrust in between the beds. Where a compara- 

 tively small amount of this melted rock came in 

 contact with the coal it changed the coal to coke, 

 but where a large amount was injected the greater 

 heat transformed the coal into graphite. This 

 transformation was effected over an area of sev- 

 eral hundred acres in Red River Valley. 



Regular Program 

 Results of a Qeodetio Study of the San Francisco 

 Earthquake: Mr. John F. Hatfobd. 

 The report of the California State Earthquake 

 Investigation Commission is now being published 

 by the Carnegie Institution. It includes a paper 

 prepared by Messrs. Hayford and Baldwin, of the 

 Coast and Geodetic Survey, giving the permanent 

 displacements detected at sixty-one old triangula- 

 tion stations, by new triangulation after the 

 earthquake. 



The permanent displacements to the northward 

 on the west side and to the southward on the 

 east side of the fault are greatest at the fault, 

 and are nearly or quite parallel to it. On either 

 side of the fault the permanent displacements 

 decrease with increase of distance from the fault 

 in such a way that lines on the surface of the 

 ground and at right angles to the fault, which 

 were straight before the earthquake, became 

 curved lines after the earthquake, concave to the 

 southward east of the fault and concave to the 

 northward west of the fault. 



At corresponding distances from the fault, espe- 

 cially near it, the displacements on the western 

 side of the fault are twice as great, on an average, 

 as those on the eastern side. 



Mr. Hayford presented some considerations 

 which lead him to believe that in such an earth- 

 quake the fault along which the displacements 

 take place should not be expected to lie in the 

 middle of the area which was under stress before 

 the earthquake and the displacements should not 

 be expected to be equal on the two sides of the 

 fault. 

 Ordovician Paleogeography : Mr. E. O. Uibich. 



Mr. Ulrich exhibited paleogeographie maps of 

 North America showing four stages of the Mo- 

 hawkian epoch. Their explanation was preceded 

 by a brief discussion of the classes of evidence 

 available in paleogeographie studies. Roughly 

 divided the facts bearing more or less directly 

 upon paleogeography comprise two main classes: 



(1) organic (composition and distribution of 

 faunas and floras) and (2) physical (phenomena 

 of stratigraphic overlap, character and distribu- 

 tion, with respect to known lands and seas, of the 

 various kinds of deposits, marine and non- 

 marine). 



The presence and direction of ancient marine 

 currents is determined primarily by organic cri- 

 teria, but in a few cases their evidence is ma- 

 terially corroborated by facts falling under the 

 physical class. It was pointed out, on the other 

 hand, that the physical criteria of stratigraphic 

 overlaps are but rarely sufficiently conclusive by 

 themselves. As a rule they require the corrobo- 

 rative evidence of organisms before the overlaps 

 may be accepted as established. In many cases 

 also the overlap was originally suggested by 

 purely paleontologic evidence, the physical evi- 

 dence being so obscure that it is easily over- 

 looked. 



Further, it was pointed out that the physical 

 criteria indicating coasts, especially of Paleozoic 

 lands, are often exceedingly inconspicuous. In- 

 dubitable instances were cited of near-shore sedi- 

 mentation, in seas submerging old lands, the true 

 significance of which might perhaps never have 

 been recognized if the beds had been unfossil- 

 iferous. 



The first step in the preparation of paleogeo- 

 graphie maps is the solution of approximately 

 synchronous facts. These must be primarily only 

 organic. With such parts as a basis and check 

 we may use orogenio movements which resulted 

 in the emergences or submergences of large epi- 

 continental areas. These movements are chron- 

 icled by the rocks and fossils, but it is the paleon- 

 tologist alone who is responsible for their chro- 

 nologic classification. Indeed, the determination 

 of the relative age of geologic phenomena, hence 

 the solutions of facts that may be reasonably 

 assumed to be approximately synchronous, is the 

 paleontologist's principal excuse for being. Con- 

 sidering his long training he may justly claim to 

 have become an expert in such solution; and it 

 is an undeserved reflection on his intelligence and 

 attainments when a non-paleontologist says that 

 a " New York formation can not be narrowly 

 correlated with an equivalent in the Mississippi 

 Valley," and that "the data of paleogeography 

 do not admit of refined definition." 



In the speaker's estimation the relative com- 

 petency of the two classes of evidence, organic 

 and physical, is, respectively, as four is to one; 

 and that the latter without the support of highly 



