.Revieios — Bulletin of the United States Survey. 179 



Above the limestone and chert series is a set of rocks known as 

 quartz slates of a distinctly fragmental texture. The iron-bearing 

 member is next above and consists of slaty and often cherty iron 

 carbonate, ferruginous slates and cherts, and actinolitic and mag- 

 netitic slates. The iron-carbonate is sometimes mingled with cherty 

 silica, sometimes the two materials are in solid bands, alternating 

 with each other. In some of the carbonates of the Penokee series 

 there still remains a large percentage of organic matter. The 

 authors further show that the deposits of iron-ore now largely worked 

 are in part due to a concentration of the carbonate of iron which 

 had been widely distributed in the higher strata. They consider 

 that the chert was simultaneously deposited with the iron-carbonate, 

 and that there has probably been an extensive re-arrangement of the 

 silica originally present. 



IV. — Bulletin of the United States GEOLoaiOAL Survey. Nos. 

 62, 65, 67 to 81. 8vo. Washington, 1890-91. 



THE latest numbers of this publication which have reached us 

 show that the United States Survey, under the able direction 

 of the Hon. J. W. Powell, still maintains its high standard of 

 excellence, and is as much a pattern to our authorities as ever, 

 save in the delay that takes place in their issue. The wide extent 

 of ground covered by these mostly bulky numbers is certainly 

 remarkable. Nothing comes amiss, provided it bears in any way on 

 the work of the Survey. Thus we have a report on the astronomical 

 work of 1889 and 1890 (No. 70). Two numbers (72 and 76) are 

 lists of altitudes ; the latter being a second edition of the "Dictionary 

 of Altitudes in the United States," and not a bad gazetteer at a 

 pinch. The "Viscosity of Solids" (73), and the "Report of work 

 done in the division of Chemistry and Physics" (78), together with 

 "Earthquakes in California in 1889, by J. E. Keeler" (68), which is 

 a continuation of the lists given by Prof. E. S. Holden up to 1888 

 in a previous number, bring the list of Bulletins that are not strictly 

 geological to an end. 



Turning next to the stratigraphical memoirs we light first on 

 Gr. H. Williams (62), " The greenstone schist areas of the Menominee 

 and Marquette Regions of Michigan," which is "a contribution to 

 the subject of Dynamic Metamorphism in Eruptive Rocks ; " the 

 greenstones, and certain intimately associated acid rocks, are alone 

 dealt with, no attention being paid to the quartzite, dolomites, or 

 shales of the younger Huronian. The conclusion arrived at is that the 

 greenstones of these areas are eruptive rocks, the foliated character 

 of which is a secondary feature. 



"The relations of the Traps of the Newark System in the New 

 Jersey region" form the subject of No. 67. Mr, N. H. Darton 

 shows that in their genetic relations these traps belong to two 

 classes ; first the extrusive sheets contemporaneous with the in- 

 closing strata, and typified by the great lava flows constituting the 

 Watchung Mountains; and, second, intrusive sheets and dikes of 

 subsequent age, of which the celebrated Palisade trap on the shore 

 of the Hudson River is an example. 



