ANALYTICAL ABSTRACTS. 645 



the New Jersey and United States Surveys. Hypothetic maps and sections 

 are given of the New Red in New Jersey, New York, Connecticut and Massa- 

 chusetts. The structure ascribed to the Connecticut field differs radically 

 from that of Davis and Griswold, being characterized by folds instead of 

 faults. All trap sheets are held to be contemporaneous. 



With the aid of these maps and other conjectures ninety-one localities of 

 fossils, ranging from Massachusetts to North Carolina, are classified with 

 reference to the five formations discriminated in Pennsylvania; and lists are 

 given of the species reported from the several localities. It is thought that 

 the uppermost and lowermost beds may differ widelv in age, the Norristown 

 being possibly as old as Permian. 



The paper is emphatic, not to say eloquent, in its characterization of the 

 fatuity of the opinions it controverts, but the dangers which lurk in rhetoric 

 are minimized by the suppression of names. 



It is only through extrapolation that the two researches are made to appear 

 discordant. If the structural results of elaborate field study in Pennsylvania 

 be compared with the results of similar work in Connecticut, substantial agree- 

 ment is found. In each district the series is very thick, has a dominant dip 

 in one direction and is expanded in outcrop by faulting. G. K. G. 



The Optical Recognition and Economic Importance of the Common 



Minerals Found in Building Stones. By Lea McI. Luquer. 



(School of Mines Quarterly, Vol. XV., No. 4, July, 1894). 



The microscopic examination of thin sections of building stones was first 



recommended by Cordier in 18 16, and H. C. Sorby was one of the first to 



successfully put it in practice. The facts determined by the microscope are 



divided into two classes: 1. Mineralogical, including (a) the component 



minerals, (//) the chemical composition of the minerals, (c) the condition of the 



minerals. 2. Physical or structural, including (a) porosity, (0) cohesion, (<r) 



homogeneity. Thirty-eight rock-forming minerals are described, and a short 



bibliography is given of the articles consulted in the preparation. T. C. H. 



Landscape Marble. By Beebe Thompson (The Quarterly Journal, 

 Geological Society, Vol. L., Part 3, No. 199, August, 1894, pp. 

 393-410). 

 The first published description of the landscape marble occurs in a work 

 by Edward Owen in 1754. The name " Cotham Stone " comes from Cotham 

 House, near which it was quarried. The stone is described as a close- 

 grained argillaceous limestone with no distinct evidence of concretionary 

 origin. The upper surface is often much wrinkled, the interior characterized 

 by dark markings. Two landscapes are shown in some specimens. The 



