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available deposits. Following this is a summary of the technology of Portland 

 cement ; notes on the chalks (Taff) and clays (Branner) of southwest Arkansas as 

 Portland cement materials; and a brief description of the Whitecliffs cement plant. 

 The subjects are well arranged ; and the section on cement technology is rather more 

 satisfactory than the material usually offered under this heading. 



The sandy basal member of the Upper Cretaceous, prominent in Texas and 

 Indian Territory, is concealed throughout its extent in Arkansas by post-Cretaceous 

 gravels and sands. The lowest member of the Upper Cretaceous visible in Arkansas 

 is therefore the marl overlying this basal sandy member. This marl is a continuous 

 formation, and increases gradually in thickness from 30 feet at Austin, Tex., to 300 

 feet at Whitecliffs, Ark. Overlying this marl is the Whitecliffs chalk, which in turn is 

 overlain by 200 feet of blue limy marl. Above this is the Saratoga chalk, which is 

 succeeded by greensands and clay marls. The Whitecliffs and Saratoga formations 

 will now be discussed in some detail, as being possible sources of Portland cement 

 materials. 



The Whitecliffs chalk is exposed, in Arkansas, in three separate areas, being 

 covered in the intervening regions by post-Cretaceous deposits. These areas are in 

 the vicinity of Rocky Comfort, Whitecliffs, and Saline Landing. In the Rocky Com- 

 fort area the thickness of the formation could not be precisely determined, but prob- 

 ably exceeds 100 feet. Farther east, at Whitecliffs, nearly 100 feet of chalk is exposed, 

 and the top of the formation is concealed. Still farther east, at Saline Landing, less 

 than half this thickness is shown. At Okolona no chalk occurs, its stratigraphic 

 position being occupied by a chalky marl. The Whitecliffs chalk therefore occurs as 

 a wedge, thickest toward the west, and coming to an end near the middle of the Creta- 

 ceous region of southwest Arkansas. 



The Saratoga chalk formation occurs 200 feet above the Whitecliffs formation, 

 and separated from the latter by marls. The maximum thickness of the Saratoga 

 chalk is 30 feet; it is exposed in three areas in Arkansas, located respectively at 

 Washington, Okolona, and Deciper. 



Analyses show that these chalks of both formations vary greatly in composition; 

 the lime carbonate varying from 49.90 per cent, to 90.01 per cent.; the silica and 

 insolubles, from 4.91 per cent, to 43.72 per cent. In one respect the specimens agree : 

 they are all sufficiently low in magnesia to come well within Portland requirements. 



Wilder, F. A. Present and Ftiture of the Ajnerican Gypsimi Industry. 



Eng. & Min. Jour., Vol. LXXIV, pp. 276-8, 4 Figs., 1902. 



Brief review of the origin and distribution, both geographical and geological, of 

 gypsum deposits; followed by a somewhat more detailed discussion of the uses of 

 gypsum and the methods of manufacture of the various gypsum products, with inter- 

 esting notes on recent German practice in the manufacture of plasters. 



Origin of the Oligocene and Miocene Deposits of the Great Plains. — 

 By J. B. Hatcher. (Proc. Am. Phil. Soc, Vol. XLI. 

 [April, 1902].) 



After an introductory statement regarding the various horizons of 

 the Tertiary deposits of the western plains, the author proceeds to a 



