g PROCEEDINGS OF THE NATIONAL MUSEUM vol.76 



Qravel Point stage — Continued. 

 Zone 3. — " Emmetensis zone." 



Bed 2. This zone is a recurrence of the lithology and fauna of the 

 lower part of zone 1. The rock is a thin-bedded, finely crystalline 

 to semimassive, brown limestone and the fossils are beautifully pre- 

 served with the calcareous shells intact. Two and a half feet from 

 the base is a slightly more shaley layer 3 inches thick carrying a 

 solitary coral fauna in addition to the typical association. This bed 

 is characterized by the large number of shells of a nacreous nature 



{FhoHdostrophia), preserved with a pinkish color 9 feet 8 inches. 



Bed 1. A sharp change in lithology accompanies the abrupt introduc- 

 tion of several new faunal elements, among which Chonetes emme- 

 tensis Winchell is the most conspicuous. The Spirifer-Stroiyfieo- 

 donta-Cystodicti/a association continues in this bed along with the 

 new introduction. The bed consists of a semimassive, flakey, buff- 

 gray, shaley limestone, with a few long, reddish, organic markings, 

 and has no true bedding planes. Frequent shale like layers a few 

 inches in thickness separate the heavy limestones toward the base 

 but the topmost foot and a half is composed of a practically barren, 

 buff-gray, shaley limestone again with worm borings__4 feet 6 inches. 

 Zone 2. — " Large Atrypa zone." 



Lower 12 inches lithologically similar to beds below but introducing a 

 new association of species, consisting of a mucronate Spirifer, concava- 

 like Stropheodonta, and Cystodicyta. Twelve inches above the base are 

 seen many worm borings, and the character of the lithology changes to 

 a brownish gray, very finely crystalline to massive, slightly shaley lime- 

 stone. The lowest beds are seemingly reworked material filling in the 

 Interspaces between the reef heads below. The predominant sediment 

 throughout this zone is of brownish-gray, massive limestone carrying 

 numerous worm borings, but is interrupted at intervals by thin bands of 

 semicrinoidal, crystalline limestone. In general, the entire zone carries 



a continuous fauna 8 feet. 



Zone 1. — Base of exposed Traverse Group in western Michigan. 



Bed 3. Dark brown, massive limestone in four bands nearly 1 foot 

 thick each separated by thin, 2-inch beds of brown to black limey 

 shale. Entire bed bituminous, very fossiliferous below with pele- 

 cypods, brachiopods, and individual corals. The top layer contains 

 enormous heads of stromatoporoids, a small digitate Favosites, and 



many Oypidulas 4 feet. 



Bed 2. Light brown to buff, shaley limestone introducing a predomi- 

 nating element of Atrypa and Gypidula, the latter often 2 inches in 

 length. Several bands carry much bituminous matter 2 feet 6 inches. 

 Bed 1. Exposed in a dome on shore one-eighth mile south of Gravel 

 Point. The basal bed is a dark brown to black, thin-bedded, shale- 

 like limestone with an abundance of crinoidal fragments and crushed 



Athyris 1 foot 2 inches. 



Above this is a lighter brown, fragmental limestone carrying a 

 heavy coral fauna composed of Prismatophyllum, small digitate 

 Favosites, Stromatopora (small mammillate type, mammillae about 

 214 mm. apart), Zaphrentis, Conocardium, and Athyris . — 2 feet. 



Essentially the same succession is encountered in the next men- 

 tioned outcrop where in addition the sequence is extended through 

 some 35 feet of younger beds. The effect of structure upon the 



