1898] SOME NEW BOOKS 209 



land. It consists of parallel mountain ranges, with deep valleys, 

 which are cut, nearly at right angles, throughout much of the distance, 

 by the Potomac river. It is divided into three districts, based upon 

 clearly defined geological differences; these are an eastern (Blue Ridge 

 and Great Valley), a central (Appalachian Mountains proper), and a 

 western (Alleghany Mountains). 



Within the relatively small limits of the State of Maryland there is 

 hardly an important geological epoch that is not represented, the most 

 important omissions being in the Jurassic, with the possible exception 

 of its later portion. The seven regions just indicated are each com- 

 posed of a distinct series of geological formations. The beds of the 

 Coastal Plain are nearly horizontal, still there is a predominance of 

 the latter Cainozoic formations in the eastern division, and of Meso- 

 zoic and early Cainozoic rocks in the western. East of Parr's Ridge, in 

 the Piedmont Plateau, is a sequence of highly crystalline rocks, largely 

 igneous, which represent the remains of a vast Archaean Continent, 

 whose detritus furnished the Palaeozoic sediments. West of Parr's 

 Eidge are greatly folded and metamorphosed, but less crystalline, 

 beds of early Palaeozoic time ; the Frederick valley, above alluded to, 

 lies in blue Palaeozoic limestone in part overlaid by the red sandstone 

 and shale of Mesozoic age. In the Appalachian region, Blue Ridge 

 and Great Valley are in Cambrian and Lower Silurian ( = Ordovician) 

 rocks, in places so eroded as to expose the Archaean iioor ; the 

 Appalachians are built of Upper Silurian and Devonian strata ; the 

 Alleghanies are composed of more gently folded Devonian and Car- 

 boniferous deposits, carrying the valuable coal seams of the Cumber- 

 land basin. 



It is thus clear that ample opportunity is afforded to Professor 

 Clark and his assistants of producing a series of memoirs of varied 

 and profound geological interest. The present volume forms an 

 excellent basis, and augurs well for the future. 



Down and Antrim for the Holidays 



Belfast and County Dow.v Railway Company. Official Guide to County Down 

 AND tiik MOUENE MOUNTAINS. By R. Lloyd Praeger, with seventy [reproductions 

 of] photographs of Scenery by R. Welch, Belfast, maps, and other illustrations. 

 8vo, xvi + 232 pp. Belfast : Marcus Ward & Co. 1898. One Shilling. 



Official (^cide to the Belfast and Northern Counties Railway, the Giant's 

 Causeway, and the Antrim Coast. Maps and illustrations. 8vo, viii + 172 pp. 

 Belfast : W. & G. Baird. 189S. Sixpence. 



THESE are two excellent handbooks for the tourist in Counties Down 

 and Antrim. Of late years a very great improvement has taken place 

 in the accommodation for visitors to the North-east and the West of 

 Ireland especially, and travel there is as comfortable as anywhere. 

 There is no better holiday in our opinion than a fortnight spent 

 between Belfast and the Giant's Causeway, with a day or two spared 

 for the Mourne Mountains. These guide-books cover theexact area, and 

 are indispensable each in itself and as supplying the gaps in the other. 

 The first on our list is compiled by the well-known President of the 

 Dublin Naturalists' Field Club, and that alone should secure it a large 

 sale. It deals in an equally able manner with the History, Archaeology, 

 Sports, Artistic merits, Natural History, and Geology, and these in no 

 mere perfunctory way. It has several maps, one of which, by Professor 

 M. F. Fitzgerald, is of great value, as it gives for the first time the 



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