292 THE GEOLOGY OF MINNESOTA. 



[Trenton limestone. 



same rock is visible and has been wrought. From this point the banks 

 of this creek become continuously rocky. 



G. W. Knight's quarry is near Fillmore, sec. 10. The stone is hard, 

 gray, compact, brittle and fossiliferous, in beds of all thicknesses, depend- 

 ing on the weathering and exposure, up to eight or more inches. It is sit- 

 uated along the ravine, approaching Fillmore. 



Geo. Shepherd's quarry is also near Fillmore, on N. E. J sec. 9, and seems 

 to consist mostly of isolated even layers in the shale that so frequently 

 accompanies the Trenton. In this shale are Chcetetes, Rhynchonella and 

 Strophomena. The stone is not of much account, owing to its being encum- 

 bered so heavily with the shale, but is very desirable for the uniformity 

 of its thickness. S. C. Pettit has a quarry of the same kind, N. E. sec. 10. 



At Chatfield the Trenton appears in the highest bluifs on the north 

 side of the village. It is made up very largely of shale, but affords also 

 some even layers that are wrought. These have the same stratigraphical 

 horizon as the stone at Minneapolis and St. Paul, but do not contain so 

 much argillaceous matter. They are much firmer and more compact, 

 though not so thick in the aggregate. Below these layers the St. Peter 

 sandstone is seen. The Trenton at this point has a gentle dip N. E., while 

 the Shakopee at the mill by the river dips N. W. The brachiopods so com- 

 mon at the falls of St. Anthony, are here seen in great numbers, and an 

 occasional specimen oiLingula Cobourgensis, Bill. The section at the quarry 

 of Dennis Jacob is made up of seven feet of limestone and shale, crumbling 

 .away, underlain by about eight feet of limestone. 



The old qujirry of Mr. Joseph Taylor, sec. 13, Fountain, has been men- 

 tioned already under the head of the St. Peter sandstone, and the exposed 

 section given. At this quarry very large cephalopods have been taken out, 

 and some fragments of galena have been encountered. The strata which 

 belong to the Trenton at this point may be more fully described thus: 



Section of the Trenton near fountain. 



1. " Upper Trenton" strata, 10 feet. 



2. Green shales, containing various species of coiled shells, brachiopods, corals, 



lamellibranchs and a small trilobite. Some of the calcareous layers em- 

 braced in this shale are charged with oolitic brown haematite, giving them 

 a very rusty color when disintegrating, 20 feet. 



8. Limestone, of a bluish gray color, with some shaly layers, 10 feet. 



4. Arenaceous and ferrugiuou* shale, 2 feet. 



