THE SWEETLAND CREEK BEDS 71 



Number Feet 



6. Concealed -.--...--..? 



5. Greenish shale (opposite the schoolhouse) - - - - 1 



4. Pyritiferous green stony layer with cylindrical straightish fucoid 



impregnations ..... ...a 



3. Green shale ... . T 



2. A conglomerate of fish teeth, containing Ptyc Modus calceolus and 

 Synthetodus frequently in a worn condition and imbedded in a 

 greenish argillaceous fine-grained dolomite ----%. 



1. Beds of the Cedar Valley limestone containing large fragments of 



Stromatopora, with the upper surface unevenly eroded. 



From this point westward no more is seen of the beds under 

 consideration until we come to East Hill, in Muscatine. Under 

 the south bluff of this hill the railroad bed has been excavated 

 in the upper dark shale seen in the foregoing sections. These 

 rise here about thirty feet above the bed of the road, and they 

 have been so disposed to slip in the bank, that piles and a stone- 

 wall have for many years been needed to keep the embankment 

 from coming down on the track. These were removed late last 

 fall and the face of the embankment was cut away several feet. 

 This work left the shale well exposed. The section above and 

 below the railroad bed is as follows. 



Number Feet 



2. Dark or gray bituminous shale, with three parallel bands of green 



shale a few inches in thickness and about three or four feet 

 apart, weathering into fine chips of a yellowish light gray color, 

 containing small flat concretions of pyrites, joints in some of 

 the freshly exposed shale filled with numerous small crystals of 

 lenite disposed in branching patterns, the basal part containing 

 sea lingula and exhibiting the peculiar network of green thread- 

 like extensions observed in previous sections near the transi- 

 tions to green shale -------- 36 



1 . Green shale ........ . . 2 



The top of number 2 is unconformably overlaid by the Coal 

 Measures, and has evidently been weathered previous to their 

 deposition. Below number 1 the section is concealed in the 

 river bank. The base of this layer is about ten feet above low 

 water. There is little doubt that it is the equivalent of number 



