814 THE AMERICAN NATURALIST. (VoL. XXXII. 
Nomenclature of Contact Rocks.'— Salomon, in his discussion 
of the geological relations of the granite massifs of the southern 
Alps lying between Piedmont and the boundary of Hungary, finds 
occasion to refer briefly to many contact rocks. . The confusion in 
the nomenclature of this most interesting of rock-groups leads him to 
suggest a simplification in the method of naming them. The less 
altered phases in the outermost zones of contact action he would 
call by the names of the original rocks from which they were formed, 
adding the word “contact” as a prefix, as “‘contact-sandstone”’; for 
the more highly metamorphosed phases, he would use “ hornfels,” 
with a suffix indicating its mineral character. Thus we would have 
a “hornfels-gneiss,” a “ hornfels-micaschist,” etc. The names edo- 
lite, astite, aviolite, and seebenite are proposed for combinations 
of mica and feldspar, mica and andalusite, mica and cordierite, and 
cordierite and feldspar. 
A large number of brief descriptions of the granite of the massifs, 
and of the metamorphic rocks surrounding them, are scattered through 
the article, which is geological rather than petrographical. 
Petrographical Notes.— Basalt occurs south of New-Lars and 
north of Kasbek in the Caucasus. Hibsch? reports the rock from 
both localities to contain phenocrysts of quartz and feldspar in a 
basaltic matrix composed largely of glass. The quartz phenocrysts 
are surrounded by aureoles of augite. The phenocryst plagioclases 
consist of rounded acid nuclei of the composition AbAn enclosed 
in peripheral zones of a more basic feldspar, Ab,Ang, of the same 
composition as the plagioclases in the groundmass. Many augite 
crystals, also, are built around nuclei of hypersthene. Hibsch explains 
the phenomena as due to the presence in the basalt of foreign quartz, 
acid feldspar, and hypersthene grains obtained from an andesite. 
Cohen ê reports the existence of a tourmaline-hornfels in the con- 
tact zone around the granite of Sea Point in the Cape States. 
The subject of metamorphism and the metamorphic rocks is 
treated critically by Van Hise‘ in an essay that discusses the 
physico-chemical and the dynamic-mass, and molecular principles 
involved in the production of highly crystallized rock types from 
glassy and clastic forms. The nature of the essay prevents its suc- 
cessful abstraction, as it is itself the abstract of a fuller treatise on 
the same subject. 
1 Min. u. Petrog. Mitth., Bd. xvii, p. 143- 
2 [bid., p: 285. 3 Ibid., p. 287- 
4 Bull. Geol. Soc. Amer., vol. Y 5 465. 
