Geology and Mineralogy. 243 



structures and it is quite improbable that a graben 4,000 feet 

 deep would be so short and end so abruptly. Moreover, the steep 

 walls which suggest faulting are satisfactorily explained by the 

 system of vertical joints. Turner's investigations support the 

 views of Becker and Branner that the Yosemite Valley " was 

 formed by river erosion facilitated by strong jointing," just as are 

 many other canyons of the Sierras. "That some faulting has 

 occurred along the sheeted or jointed zones of granite about the 

 Yosemite is probable, but it is thought that this has resulted 

 rather in a more thorough shearing of the granite than in the 

 dropping down of wedges. Along such a sheared zone, the 

 streams would rapidly deepen their beds. Even where the rocks 

 are not sheared, but merely intersected with vertical joints, it is 

 easy to see how, as erosion progressed, the slabs would crumble 

 or tumble off along the joint planes, leaving vertical faces. If 

 now a tongue of ice should pass through the valley and clear out 

 the talus and other detritus and round off the projecting shoulders 

 and spurs, and as it retreats leave terminal moraines as barriers 

 to form the valley floor, we seem to have sufficient means for the 

 accomplishment of all we now see in Yosemite Valley." (Pp. 

 319-320.) H. E. G. 



6. Geologishes Centralblatt / Anzeiger fur Geologie, Petro- 

 graphies Palaeontologie, unci verwandte Wissenschaften ; edited 

 by K. Keilhack. Vol. I, No. I, 32 pp., 8°. Leipzig (Gebrueder 

 Borntraeger). — This new journal has for its object the prompt 

 publication for those interested of brief abstracts of all important 

 contributions in geology and its allied sciences. A special 

 endeavor to accomplish this with the least possible delay is prom- 

 ised. The abstracts will appear in German, English and French. 

 In addition to the editor-in-chief, the names of seventy-eight 

 geologists, from all parts of the world, are given who will aid in 

 conducting the journal. The numbers are to appear every two 

 weeks. There can be no doubt that a publication of this kind, if 

 well carried out, will prove highly useful, and we wish it all suc- 

 cess, l. v. p. 



7. Metasomatic Processes in Fissure Veins ; by Waldemar 

 Lindgren. (A paper read before the American Institute of Min- 

 ing Engineers, Feb., 1900. Author's edition.) — The purpose of 

 the paper, as expressed in the author's own words, is to collect 

 the scattered data relating to the alteration of rocks near fissures, 

 to indicate the principal active processes, to classify the veins, if 

 possible, according to the different phases of alteration accom- 

 panying them, and finally to draw some conclusions from the facts 

 thus grouped. In Part II of his paper Mr. Lindgren discusses 

 the various minerals developed by metasomatic processes in min- 

 eral veins, giving the origin, mode of replacement, etc. In Part 

 III he proposes fourteen different classes into which fissure veins 

 may be divided, naming each class according to the principal 

 metasomatic process found in it. Each class is discussed and 

 examples cited. For instance, Class No. 8 is that of Sericitic 



