GEOLOGY OF SOUTHWESTERN IOWA 525 



On the Baylor and Mann farms twO' miles south of Thurman, 

 on the bluff road, are found outcrops of a sandstone separated 

 from an overlying limestone by a shale two feet thick. Udden in 

 the ]\Iills and Fremont counties report, Volume 13, Iowa Geolog- 

 ical Survey, gives a composite section of these outcrops, and as 

 his lithogical descriptions are unusually perfect his section will 

 be given verbatim. 



• XV. SECTION IN THE BLUFFS TWO MILES SOUTH OF 

 THURMAN. 



Feet 

 6. Bluish, gray sandstone of fine texture cemented by a 

 crystalline calcareous matrix i 



5. Gray shale, not calcareous, evidently in part originally 



a black shale 10 



4. A dark gray blotched limestone cut by straight and ver- 

 tical joints into large blocks and containing numerous spher- 

 oidal lumps about one-fourth inch in diameter. In section is 

 seen to be composed of an agglomeration of indurated lumps of 

 calcareous mud, of all sizes up to one-half inch in diameter, 

 and in varying color due to weathering. The larger of these 

 are themselves occasionally composed of agglomerations of 

 smaller nodules. Some show shrinkage cracks and fissuring. 

 In this mass are a few shell fragments, joinis of crinoid stems 



and quartz grains 3 



3. Soft bluish gray shale, partially concealed 2 



2. Grayish blue sandstone of fine texture and indurated by 

 a crystalline calcareous matrix, in straight lines below, ripple 

 marked above 3 



1. Shale, not well exposed 1 



Lower strata found in a coal prospect shaft near one of the 

 outcrops continue the section to the N>nnan coal. 



RECORD OF BAYLORS SHAFT SOUTH OF THURMAN. 



Feet Inches 



6. Blue limestone 3 



5. Sandstone 5 



4. Shale 20 



3. Limestone 6 



2. Coal, Nyman 1 2 



1. Shale and sandstone 



Total 29 8 



This coal has also been prospected on the Mann and McCart- 

 ney farms farther north toward Thurman and found to have a 

 thickness of six inches to one foot. In the distance from these 

 outcrops to Thurman the same strata are found in numerous out 

 crops along the bluff road. From Plum creek no outcrops are to 

 be seen until the north line of the village of Thurman is reached 

 where the same strata are again exposed in outcrop. For a dis- 

 tance of one-half mile north of this locality the sandstone ledge 



