3 o6 REVIEWS 



in locating a plant. The remainder of the report takes up by counties 

 the results of field work and contains maps of limestone and clay areas 

 with analyses of samples from them. 



In the eastern part of the states metamorphic limestones of doubt- 

 ful age are found only as erosion remnants surrounded by basalts and 

 granites. Deposits of economic importance are limited to four counties. 

 Very little stone approaching natural cement rock is found in the state. 

 The analyses show the limestones to be low in magnesia and silica. The 

 latter probably averages less than 5 per cent. Analyses of adjacent 

 clay and shale deposits are given in each case, and some estimate can 

 be made of the possibility of proper mixtures for Portland ratios. 



In western Washington sedimentary rocks predominate, but lime- 

 stone is limited to a few localities in the north. Its quality is very 

 similar to that farther east. 



Taking the state as a whole, localities in which limestone and clay 

 or shale outcrop in close proximity and favorably situated relative to 

 transportation are few. At the time the report was published, five 

 plants were in operation and two under construction. 



W. B. W. 



The Road and Concrete Materials of Iowa. By S. W. Beyer and 

 H. F. Wright. Iowa Geological Survey, Annual Report, 

 1913. Pp. 33-685, figs. 65, pis. 63, tables 8, maps 2. 



Great development in road-building and concrete construction has 

 led to widespread search for materials during the last decade, and justifies 

 detailed examinations by the states of such resources. This report takes 

 up by counties the character, amount, and availability of these materials 

 over the entire state. Some reference is made to all the more important 

 localities, but the records are more complete for the counties poorer in 

 such materials than for those richly supplied. 



Nearly three-fourths of the counties in the state have deposits of 

 sand and gravel of economic importance. Gravels of two interglacial 

 epochs are of considerable value. The Aftonian gravel is worked only 

 in southwestern Iowa, because elsewhere it is too deeply buried. The 

 type of locality for Aftonian is in Union County. The Buchanan gravel 

 is available in the northeastern part of the state and is second only to 

 the post- Wisconsin gravels as a source of road and concrete materials. 

 It is found chiefly as a valley phase of outwash and the type locality 

 is in Buchanan Countv. 



