428 Reviews — Dr. W. H. Ball — Mollusca from Florida. 



4. Oil and Gas in the Western Part oe the Olympic Peninsula, 

 State oe Washington, U.S. By C. T. Ltjpton. (Bull. 581 B, U.S. 

 Geol. Surv.) — The country examined is composed of a strongly folded 

 suite of Cretaceous and Lower and Middle Tertiary rocks, almost 

 wholly covered by Pleistocene deposits. The exposures are rare, 

 being confined to sea-coast and rivers, and the country densely 

 wooded. It is hardly surprising that the author's idea of the general 

 stratigraphy and of the structure, after such a short visit, is hazy in 

 the extreme, and the account degenerates into a painstaking but 

 tedious catalogue of dips and strikes. 



The fact that oil and gas certainly exist, and that this region lies 

 in the same trend-line with the rich Californian field, indicates that 

 the region is worthy of careful investigation. 



5. Oil Shale of North- Western Colorado and North-Eastern 

 Utah. By E. G. Woodruff and David T. Dax. (Bull. 581 A, 

 U.S. Geol. Surv.) — The oil-bearing shale forms a part of the Green 

 Biver formation, and occurs as beds of variable thickness up to 

 80 feet and is of lenticular shape, the whole outcrop extending over 

 100 miles in length along a sinuous escarpment. 



The authors' description of the shale proves that the latter differs 

 materially from the usual oil shale of Scotland, in that the large 

 proportion of the bituminous matter occurs as free oil impregnating 

 the shale. It is very questionable whether the authors' claim that 

 the results of their experimental retorting have a limit of error of 

 merely 20 per cent is borne out by experience. Distillation with 

 small experimental retorts never yields the same results as with 

 modern commercial apparatus, and, merely by the introduction of 

 steam into the distillation, the yield of oil can often be increased by 

 50 per cent. 



Finally, the economic aspect of the problem is largely dependent 

 on an important factor which the authors appear to have overlooked, 

 i.e. the yield of ammonia, and it is a pity that more data on this 

 important factor have not been given. 



6. The supposed Oil-hearing- Abeas of South Australia. 

 By Arthur Wade, D.Sc. (Bull. 4, Geol. Surv. S. Australia.)— The 

 district examined forms the coastal regions near Spencer Gulf and 

 Kangaroo Island. The country is floored by an interesting series of 

 pre-Cambrian metamorphic rocks — with local patches of Cambrian 

 and Permo-Carboniferous glacial beds, and a thin veneer of Tertiaries 

 — not a very hopeful region for the oil prospector. The author 

 proves that all the reported oil shows are based on misapprehensions, 

 and a large portion of the paper is devoted to the disillusionment of 

 the general public on certain deeply rooted fallacies regarding the 

 occurrence of oil. Eor the rest the paper adds little to our knowledge 

 of the general geology. . 



III. — Oligocene Mollusca from the Silkx Beds of Florida. 



DB. W. H. DALL has recently issued an exhaustive treatise on the 

 Molluscan Fauna of the Orthaulax pugnax zone of the Oligocene of 

 Tampa, Florida, which forms Bulletin 90 of the United States 



