272 The Ohio Naturalist. [Vol. VIII, No. 5, 



places along Auglaize and Maumee Rivers and a calcareous laver 

 occurring near the base of the formation was formerly used in 

 the manufacture of cement at Defiance. 



These Devonian outcrops received some attention from the 

 members of the State Geological Survey during the seventies and 

 a report of their work is given in the publications of the Sur\'e\' 

 at that time. A section which escaped notice, probably because 

 it was then largely covered, is to be found along Ten Mile Creek. 

 This stream flows across the northen portion of Lucas Count v and 

 empties into Maumee Bay at the state line. Near Silica, eight 

 miles west of Toledo, the creek crosses a slightly drift co\-ered 

 limestone ridge which extends southward from Michigan into 

 Oiho. During the summer of 1906, the channel was artificialh- 

 deepened and at that time an excellent outcrop of rock was laid 

 bare. The section is similar to that discussed bv G. K. Gilbert''* 

 except that it includes more of the Devonian. It is to these 

 upper strata of the following section that particular attention is 

 called since they rarely outcrop in northwestern Ohio. 



SECTION ON TEN MILE CREEK. 

 Devonian 



Delaware limestone {Traverse). 



14. Massive compact bluish drab limestone contain- 

 ing iron pyrites, traces of petroleum and a few 

 fossils 10' 



1 ;>. Thin unevenly bedded blue limestone with several 



layers of white chert, both fossiliferous 3' 



12. Blue shale and soft shaly limestone containing 



much iron pyrites and quite fossiliferous. ... 2' 0" 



1 1 . Bluish gray limestone alternating with layers of 



fossiliferous white chert 3' (i" 



10. A rather compact drab limestone with manv fos- 

 sils, occurring as casts, and a considerable 

 amount of fossiliferous white chert 2' 



9. Bluish gray shaly limestone with irregular layers 

 of fossiliferous white chert. At places much 

 of this zone becomes a mass of corals 2' 



8. Rather thick and some thin layers of blue lime- 

 stone inter-bedded with soft blue slialy layers 4' 



7. Covered interval, probably in large part shah', 

 since a number of rather large pieces were 

 dredged from the bottom of the creek for some 

 distance down stream. It includes the con- 

 tact of the Delaivare with the imderl\-ing 

 formation 20' + 



(2) Report of the Geological Survey of Ohio, vol. 1, pt. 1, p. .57G. 



