SINKING OF Tin: CIUCRKS 123 



section is, however, more sillcious in character tlian the same division on 

 the east side of the Hills, and its thickness also appears here considerably 

 greater than elsewhere. 



Between the cafions which divide the monoclinal ridge good points for 

 studying the strata are not often met with, for they dip regularly from the 

 axis of the Hills, and the surface forms an undulating slope on wdiicli the 

 component strata are inseparable. 



On Burntwood Creek, which has nowhere cut the older sedimentary 

 rocks very abruptly, the Carboniferous is poorly exposed, but on French 

 Creek, the next in order, although the belt of Carboniferous is naiTowed, 

 fair exposures are exhibited. A section showing the junction of the Pots- 

 dam and Carboniferous and a bluff of the white limestone has already 

 been given on page 90. A short distance below the place of this section 

 the dip increases, and the rocks are carried down to the bed of the stream 

 near the point of its sinking. Within a short space the various members of 

 the Carboniferous are exhibited in the walls of the cailon. They are all 

 readily recognized and distinguished, but their exposures are not well 

 placed for measurement. Above them in irregular order follow the mem- 

 bers of the Red Bed series. 



In the canons of Battle and Whisky Creeks the Carboniferous lime- 

 stones are well exposed, and in the cailon of Spring Creek a most excellent 

 section is cut through the series for a considerable distance, as also on Rapid 

 Creek. The limestone strata of the gray and silicious divisions are exposed 

 on Spring Creek in a cliff 335 feet in height, and beneath them are 20 feet 

 of pink calcareous sandstones, which rest conformable upon the Potsdam 

 sandstones below. The jjinkish, lamellar limestones, or calcareous sand- 

 stones contain the usual abundance of crinoidal fragments, with cyatho- 

 phylloid corals, a Spin/era like S. Bocky-montana, and a Productus. The 

 Carboniferous belt is here about four miles in width, and — a feature com- 

 mon to most of the creeks of the Hills — the w^ater sinks at a point near 

 where the massive limestones dip under the creek bed. 



The peculiarity of the sinking of the creeks of the Hills is worthy of 

 remark, for as a rule all the numerous creeks that rise in and flow from the 

 Hills sink before reaching the Plains. There are but four exceptions — 



