IOWA ACADEMY OF SCIENCES. 27 



pheric agencies. The composition of the strata themselves is different. Here are 

 not only numerous places where solid sandstone graduates into shale or into sand, 

 but also places where sandstone graduates into clay, and places where the same 

 strata differ in thickness. If the relation of the strata is correctly represented, six 

 different seams of coal are here represented, all but one cut by erosion and varying 

 in thickness, one, especially, a foot and a half thick thinning completely out in a 

 mile and a half, its place being taken by a foot and ten inches of sandstone. 



The change in the strata due to the decomposition of the sandstones is readily 

 understood; the surface water percolating through the soil leaches out the iron 

 oxide m the stone thus allowing the stone to crumble to pieces. The change from 

 sandstone to clay in this particular locality seems to be due to differences in the 

 direction and velocity of currents, while the same changes of elevation in the 

 earth's crust that submerged the swamps and raised them aboye the water, also 

 aided in varying the margins of the sand deposits. 



Close tO'the western boundary of Warren county the river strikes against the 

 hills which are here more precipitous than to the eastward. About three miles 

 southeast of Winterset we find the section represented by the left diagram. The 

 sandstone stratum lowest in this diagram I judge to belong to the "Middle Coal 

 Measures," and to mark the division between the "Middle" and "Upper Coal." 

 This stratum of sandstone you noticed continued in adjoining out-crops. The 

 ledge of marble shale twenty feet in length is clearly a continuation of correspond- 

 ing strata measured by White at Winterset three miles further on. 



Near the mouth of the river indications of coal are much more abundant than 

 further up the river. The last diagram on the right presents a section found one- 

 fourth mile east of a bridge near Clarkson, though the strata were traced by out- 

 crops along the bluff from this point to Ford, four miles further on. In the side 

 of this bluff are to be found numerous entries near Ford, in one of which at a dis- 

 tance of fifty feet from the face of the blutf, three and one-half feet of pure coal 

 was measured, the out-crop in the face of the bluff being two and a half feet. 



ANALYSIS OF WATER FOR RAILWAY ENGINES. 



BY C. O. BATES, CEDAR RAIMDS. 



The following is one of a hundred analyses made along the Burlington, Cedar 

 Rapids & Northern Railway. Nearly all the samples are from the State of Iowa. 

 The analysis is supposed to explain itself so far as the results of such an analysis 

 are concerned. 



