444 abstracts: engineering 



beds are rearly horizontal to an area on the west in which the rocks 

 have been severely compressed into folds and broken by faulting. 



In the area of nearly horizontal rocks there are six large anticlines 

 whose structure is probably continuous in depth far enough to form 

 traps in sands in the Virgelle, Colorado, and Kootenai formations. 

 The belt of disturbed rocks in the Cretaceous and Tertiary (?) forma- 

 tions adjacent to the mountains in the Birch Creek-Sun River area 

 is a small part of a large structural province that extends northward 

 far beyond the Canadian boundary into Alberta, a distance exceeding 

 200 miles, and southward to the valley of Dearborn River. 



R. W. Stone. 



ENGINEERING. — Physical and chemical tests on the commercial 

 marbles of the United States. D. W. Kessler. Bur. Stand. Tech. 

 Paper No. 123. Pp. 54, pis. 7. 1919. 



This paper is the first report of the Bureau of Standards in connec- 

 tion with an extensive cooperative program for investigating the build- 

 ing stones of the United States. The other government departments 

 participating in the work on different phases of this investigation are 

 the U. S. Geological Survey, Bureau of Mines and Bureau of Public 

 Roads. 



This paper comprises the results of strength tests, water absorption, 

 porosity, specific gravity, freezing, thermal expansion, electrical con- 

 ductivity and chemical tests on 52 different types of marbles produced 

 in this country. The purpose of the work is to determine the relative 

 value of the different types for building purposes and other special 

 uses. 



Compressive strength tests were made on specimens in the original 

 condition and on specimens after being soaked in water for two weeks. 

 The strength of the dry specimens gave values ranging from 7850 to 

 50205 lbs. per sq. in. As a rule the soaked specimens gave lower 

 compressive strengths than the dry, and in a few cases the loss due to 

 soaking was over 25 per cent. 



Transverse and tensile strength tests are included and show the 

 strength of the specimens when broken perpendicular and parallel 

 to the bedding planes. 



The freezing tests made for this report consisted in determining the 

 loss in weight and strength due to 30 freezings and thawings. While 

 these losses were considerable in most cases, some samples showed 

 practically no loss and occasionally a gain in strength was indicated. 



