374 THE GEOLOGY OF MINXESOTA. 



[Drift. 



8. Beds of argillaceous limestone, each of about eight inches and separated by 

 shale beds, each of the latter being about two inches, containing Iteceptacu- 



lites 5 ft. 2 in. 



9. Shale 4 in. 



10. Vesicular limestone, argillo-magnesian, in one bed 9 in. 



1 1 . Shaly and calcareous beds (thin) 8 in. 



12. Crystalline beds of a gray color, weathering buff , one bed 1 ft. 7 in. 



13. Shale and shaly limestone 1 ft. 4 in. 



14. Shale 8 in. 



15. Argillo-magnesian limestone, some parts crystalline and calcareous only: in 



three beds 6 ft. 4 in. 



16. Shale 4 in 



17. Argillo-magnesian; one bed 10 in. 



18. Shale. i ft. 2 in. 



19. Hard crystalline limestone of a gray color with some cavities and specimens 



of Rcceptaculites 2 ft. 2 in. 



20. Shale 6 in. 



21. Argillo-magnesian, one bed; showing Chcetetes and fucoids of the Trenton 



epoch 1ft. 6 in. 



22. An interval, not well seen, of beds of greenish-blue shale and argillaceous 

 limestone, each varying from eight to twelve inches, showing abundant 

 fossils of the Trenton 16 ft. 



23. Blue, earthy limestone; under water and not well seen 6 in 



Total 103 ft. 10 in. 



In Canisteo township, due south from Kasson, is an exposure of the Galena limestone 

 at the crossing of one of the branches of the Zumbro, and along the stream for some distance be- 

 low. It appears in heavy, coarse, cavernous layers eight to sixteen inches thick, of a buff color, 

 and without apparent fossils, and has been slightly opened by quarrying. 



Rock that resembles the Galena is used at Concord for building stone, and by the farmers 

 for foundations between Concord and Mantor\ille. 



THE DRIFT. 







This covers nearly the whole county. Boulders are abundant and 

 sometimes very large, as has been stated under the head of topography. A 

 stony blue clay underlies the southern and western portions of the county, 

 and its tenacious and impervious character is the cause of numerous marshes 

 in that part of the county. This clay is uniformly met in digging wells, at 

 the depth of from ten to thirty feet, and sometimes it contains logs and 

 other vegetation. While it is essentially a drift-clay, probably, in nearly 

 all cases it is augmented by the disrupted and disseminated shaly beds of 

 the Cretaceous, which has added largely to the thickness of the drift-clay 

 in other counties. These characters fade out toward the northeast, in 

 Dodge county, so that the drift-clay loses its blue color, and all the ma- 

 terials of the drift are affected by yellow loam that there takes the place 

 of the drift-clay. 



