272 
The Ohio Naturalist. 
[Vol. VIII, No. 5, 
places along Auglaize and Maumee Rivers and a calcareous layer 
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 Survey 
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 County and 
empties into Maumee Bay at the state line. Near Silica, eight 
miles west of Toledo, the creek crosses a slightly drift covered 
limestone ridge which extends southward from Michigan into 
Oiho. During the summer of 1906, the channel was artificially 
deepened and at that time an excellent outcrop of rock was laid 
bare. The section is similar to that discussed by G. K. Gilbert 2 
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' 
13. 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' 6" 
11. Bluish gray limestone alternating with layers of 
fossiliferous white chert. 3' 6" 
10. A rather compact drab limestone with many 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 shaly layers 4' 
7. Covered interval, probably in large part shaly, 
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 Delaware with the underlying 
formation. 20' + 
(2) Report of the Geological Survey of Ohio, vol. 1, pt. 1, p. 576. 
