REVIEWS 91 



limestones, marls, shales, clays, gypsum, and fuel supplies of Michigan, in connection 

 with the cement industry. Following these are notes on factories, processes, product, 

 etc. The sections on materials will be summarized. 



Limestones from two formations (Dundee and Traverse) have been used in 

 making Portland cement, while other limestones may be so utilized in the future. The 

 Dundee limestone occurs at the base of the Devonian, and contains at least one bed 

 of sufficient purity to be used in Portland manufacture. Material from this bed is 

 utilized by the Michigan Alkali Co. at Wyandotte. The limestones of the Traverse 

 group (Devonian) are used in the manufacture of Portland cement at Alpena. 



Certain Silurian limestones may furnish a natural cement, while Eo-Carboniferous 

 limestones, not at present used in Portland cement manufacture, are sufficiently low in 

 magnesia to be a possible future source of Portland material. 



Marl deposits of great area and depth occur abundantly on the lower peninsula 

 of Michigan. A map of this portion of the state showing the location of the best- 

 known deposits and of actual and proposed Portland cement plants, is presented. 

 Numerous analyses of Michigan marls are given, and their physical properties, chemi- 

 cal composition, and probable origin are discussed in detail; the conclusions of Davis 

 as to origin being restated and carefully considered. 



Shaes of the Traverse (Devonian) and Coldwater (Carboniferous) formations 

 are used in Portland cement manufacture ; the former at Alpena, the latter at Union 

 City and Coldwater. The Antrim shales of the Devonian and the Saginaw shales of 

 the Carboniferous, are referred to as of possible use. 



The surface clays are, in general, too sandy to be of use in cement manufacture, 

 though they have been so used at Wyandotte. Several Michigan cement plants obtain 

 their clay from Ohio. 



Most of the gypsum used in the Michigan cement plants is procured from the 

 extensive deposits near Grand Rapids. 



The coal used is mostly from Ohio and Pennsylvania, though Saginaw Valley 

 coal has been used to a small extent. 



During the year 1900 five Portland cement factories were in operation in Michi- 

 gan, while several others were in course of construction. Of those in operation, four 

 were equipped with rotary and one with dome kilns. As regards materials, two plants 

 used marl and clay ; two, marl and shale ; while one plant used precipitated lime 

 carbonate (caustic soda waste) and clay. Only one of the plants in construction is 

 designed to use limestone and shale ; the others using marl with clay or shale. 



Struthers, J. The Production of Gypsum in igoi . Extract from Mineral 



Resources U. S. for igoi. 8vo, pp. 13, 1902. 



An amount of 659,659 short tons of gypsum, valued at ^1,577,493, was produced 

 in the United States during 1901. Of this amount, 521,292 tons were calcined, the 

 remainder being largely used as land plaster. 



Taff, J. A. Chalk of Southwestern Arkatisas ; with Notes on its Adapta- 

 bility to the Manufacture of Hydraulic Cements. Twenty-second Ann. 

 Rep. U. S. G. S., Part III, pp. 687-742, Pis. XLVII-LIII, Figs. 57-69. 

 1902. 

 Descriptions of the general geography and geology of the region are followed by 



a detailed discussion of the two chalk-bearing formations, with local details of the 



