Revieivs — MialVs Guide to the Leeds Museum. 373 



perfect confidence to tlieir almost inexhaustible Coal-fields, which are, 

 practically speaking, unworked, so great hitherto has been the supply 

 of surface-fuel in the clearing of boundless forests, now changing 

 into broad fields of corn and pastures for vast herds of cattle. 



The older rocks, named Eozoic by the authors, comprise all the 

 formations earlier than the Paradoxides-hQ^s, including the oldest- 

 known metamoi-phic Appalachian Schists. 



Above these occur the subdivisions of the Paleozoic rocks, in- 

 cluding the Silurian, Devonian, and Lower Carboniferous, the Coal- 

 measures and the Permo-Carboniferous rocks. These rocks, it will 

 be observed, occupy a very large district in the Eastern States, but few 

 being found in the Western Territories (and those being Devonian), 

 from which it will be seen that the Carboniferous series are chiefly 

 confined to the same Eastern area. 



The Triassic and Jurassic rocks appear to occupy, on the map, a 

 comparatively limited portion of the whole country, whilst the Upper 

 Mesozoic or Cretaceous rocks cover a very extended central area 

 and also a narrow band on the Pacific coast, as well as in the south- 

 east and north-east, where it borders the older Paleozoic rocks of the 

 Mississippi and New Jersey. 



The Cainozoic series occupy not only a large portion of the 

 central region, but also spread over a,nd fill up the depressions amidst 

 the older rocks of the western mountain-ranges, in which district 

 also the chief masses of the igneous rocks are found, for there 

 appear to be no traces of them marked on the map in the Eastern 

 districts. These volcanic rocks are classed, in the explanation of 

 colours given on the map, under the Cainozoic jDcriod. 



Perhaps the remarkable progress of the United Sta,tes Geological 

 Surveyors, is most clearly indicated by the great additions made to 

 our knowledge of the several formations composing the vast Western 

 Territories of the Union, and by the better defined areas of the 

 Silurian, Devonian, and Laurentian rocks in the Eastern States. 



Contrasted with the older map by Prof. Eogers (given in Keith 

 Johnston's Physical Atlas, 1855), the colouring of the new map 

 appears somewhat too heavy and opaque, rendering names of places 

 less easily legible ; but this is probably a fault of the earlier copies, 

 which is sure to be remedied in the later printed ones, or, in a new 

 edition. The adoption of cosmopolitan terms for the great rock- 

 formations, in place of the fantastic ones used by Rogers, but now 

 generally discarded, is a very important step towards a universally 

 accepted rock nomenclature, which will prove of enormous benefit to 

 geological science the world over. 



rV. — Descriptive Guide to the Fossil CoLLECTioif in tete Museum 

 OF the Leeds Philosophical and Literary Society. By L. 

 C. MiALL. (Leeds, 1873.) 



THIS very cheap and useful guide will be of great service to those 

 who may visit the fine collection of Fossils in the Leeds 

 Museum, as it contains in a small compass much valuable informa- 



