638 PETROLOGICAL ABSTRACTS AND REVIEWS 



and a rock-name are compounded to form a name of 'specific' signification, 

 these should be joined by a hyphen; e.g. biotite-granite." With the usage of 

 porphyry in the sense of the U.S.G.S., porphyritic rocks are defined as granite 

 porphyry, diorite porphyry, etc., but the British committee says, "The name 

 granite-porphyry is ambiguous, and should not be used." Why ambiguous 

 is not clear, unless it is thought possible that it may be confused with porphy- 

 ritic granite. But porphyritic granite and granite prophyry are quite different 

 things. It is recommended that adamellite be discarded, or only used for acid 

 members of the monzonite series, and monzonite is to be restricted to rocks of 

 the type occurring in the Monzoni district. If monzonite is used in the original 

 sense of de Lapparent for the Monzoni rocks, it is a collective name and 

 embraces monzonites Brogger, gabbros, and pyroxenites. Personally the 

 reviewer would like to see the intermediate rocks, monzonite and adamellite, 

 dropped (see Jour. GeoL, XXVII [1919], 38, and XXVIII [1920], 229), and the 

 term granodiorite returned to its original sense {Jour. GeoL, XXVII [1919] 168). 

 The latter recommendation is also made by the British committee. The usage 

 of the term panidiomorphic by the British committee (following Rosenbusch) 

 as given in the definition of aplite, is regarded by the reviewer as incorrect. A 

 panidiomorphic rock would be one in which aU of the constituents have their 

 own crystal boundaries. Such a rock is almost inconceivable: and the texture 

 of apUte is as far removed from this as it can possibly be, for it has a saccharoi- 

 dal texture, that is, one in which all of the constituents are xenomorphic 

 (allotriomorphic) ; it is, consequently, panxenomorphic or panaUotriomorphic. 

 The British committee recommend the terms allotriomorphic and idiomorphic 

 in preference to xenomorphic and automorphic. The latter, however, have 

 priority by one year. The term essexite "is retained for rocks practically 

 identical with, or which show but slight divergence from, the original type of 

 Salem Neck, Essex Co., Massachusetts," which is a large order since the 

 original locality shows such a divergence of type. It is recommended that 

 diabase be dropped and dolerite used. One is as bad as the other. Diorite 

 and gabbro are given the meanings accepted in the United States (namely 

 separated on the basis of the feldspar), and Barker's usage is not followed. 

 Leuco- as a prefix for leucite, as used by Lacroix, is put in the discard. The 

 less exact terms basic, intermediate, and acid are used in preference to sub- 

 sUicic, mediosUicic, and persilicic of Clarke. 



Powers, Sidney. A Lava Tube at Kilauea. Private Publication. 

 Pp. 7, pis. 5. 



Describes a lava tube, extending from the Kaluaiki pit crater in a north- 

 easterly direction for 1,494 feet with a drop of 73 feet. The maximum height is 

 20 feet, the maximum width 22 feet. In the roof of the tube there are more 

 than a dozen small, conical cupolas "blow-piped" by gas escaping from the 

 lava. These cupolas vary from i to 8 feet in height and with similar basal 

 diameters. Thirty-three cross-sections, drawn to scale, are given. 



