Reviews — Devonian System in Maryland. 89 



YII. — Maryland Geological Sukvey. 



UNDER the direction of the State Geologist, Dr. William Eullock 

 Clark, two handsome volumes of letterpress and one of plates, 

 on the Devonian System of Maryland, have been issued (1913). 

 They form vols, v to vii of the series of reports dealing with the 

 systematic geology and palaeontology of the State. 



Vol. V, Loiver Devonian (pp. 560, with 17 text-figures and 

 16 plates, also 82 of fossils in atlas), opens with an instructive 

 and interesting Introduction on the General Kelations and the 

 Paleography of the Devonian, with an Historical Review and 

 Bibliography, by Drs. C. K. Swartz and C. Schuchert, and Professor 

 C. S. Prosser. Attention is first drawn to the original labours of 

 Sedgwick and Murchison, aided by Lonsdale, in the foundation 

 of the Devonian System, but, as justly remarked, the limits of the 

 system "were not clearly defined", and indeed with regard to the 

 Silurian junction no evidence was to be found in Devonshire. 

 Owing to the folded and faulted structure of the English area, the 

 true succession of the subdivisions and their respective faunas could 

 not be distinguished, but subsequent researches of many geologists 

 in the Rhine Valley, in Belgium, the Ardennes, the Hartz Mountains, 

 and in Bohemia have established the sequence on a firm basis, and 

 it has become " the type of the Devonian System of the world ". 



The authors point out that the Devonian of Eastern America was 

 first critically studied by James Hall, aided by de Yerneuil, wlien 

 they included the strata from the Catskill down to the Oriskany 

 Sauiistone as Devonian ; while at a much later period Kayser 

 demonstrated the Lower Devonian age of the Helderberg (Lower 

 Helderberg of Hall), and this conclusion has been more fully con- 

 firmed by Drs. J. M. Clarke and C. Schuchert. 



In a map showing the distribution of the Devonian in Maryland, 

 and in a table in the text, the following subdivisions are recognized : — 



Upper 



Catskill red sandstone Formation. 



Chemung Sandstone. 



Jennings Formation 



I Parkhead Sandstone. 

 1 Woodmont Shale. 

 L Genesee black shale. 



Hamilton Shale. 

 Middle . Eomney Shale . . \ Marcellus black shale. 



Onondaga Shale. 



, ^ . , CI 1 i. r Eidgely Sandstone. 



f Oriskany Sandstone | ^^^^J^ ^^^^^_ 



Lower - C Becraft member. 



TT , , , T • i. New Scotland member. 



I Helderberg Limestone- Coeymans member. 



I Iveyser member. 



The following statements contain so much of general interest that 

 it appears desirable to quote them at some length : — 



"The Devonian of Maryland forms a part of the Appalachian 

 Province which extends from New York southward in the Appa- 

 lachian Mountains and Plateau. The resemblance of the formations 

 to those of the northern part of the area is so close as to establish 

 their essential identity both in lithology and fauna, and hence 



