in the Triassic of North America. 95 



Section on Eagle River, Baker County, Oregon. 



Thickness 



Oh 

 P 



Massive limestone without visible fossils. 



Dark brown argillaceous shales, with Halobia cf . austriaca, 

 and other species of Halobia, and Daonella ? 



Thin bedded limestone, with banks of corals, Thecosmilia 

 norica Freeh, Spongiomorpha cf. acycliea Freeh, Mont- 

 livaultia norica Freeh, Heterastridium conglobatum 

 Reuss. 



Barren shales. 



Massive limestone without fossils. 



Calcareous shales, with Halobia cf. superb a, H. cf. salina- 

 rum, H. cf . austriaca, Dittmarites sp. ? etc. 



60 ft. 



100 ft. 



40 ft. 



300 ft. 



100 ft. 



30 ft. 

 visible 



Some years ago Mr. II. W. Turner discovered some corals 

 in limestone in Dunlop Canyon, Pilot Mountain, near Mina, 

 Esmeralda County, Nevada. These were sent to the writer, 

 who pronounced them Jurassic, as reported by J. E. Spurr* 

 upon this identification. A recent examination of these corals 

 has shown them to be more probably of Upper Triassic age, 

 which is in perfect accord with the stratigraphy. The species 

 determined are : Montlivaidtia cf. marmorea, Astrocoenia cf. 

 Waltheri, and Pentacrinus sp. indet. The two species of 

 coral are well known forms in the Noric beds of the Alps, and 

 Astrocoenia Waltheri occurs also in the Noric coral zone of 

 Shasta County, California. The Lower and Middle Jurassic 

 of the Great Basin area are not known in the coral-reef facies 

 anywhere. 



A few years ago Dr. G-. C. Martin, of the U. S. Geological 

 Survey, discovered in the region of Cook's Inlet, Alaska, some 

 coral-bearing limestones. Among the specimens sent by Dr. 

 Martin from this locality the writer has determined : Isastraea 

 cf. profunda, Thecosmilia cf. feneslrata, Phyllocoenia cf. 

 decussata, P. cf. incrassata, Astrocoenia cf. Waltheri, Mont- 

 livaultia cf. Mojsvari, and Spongiomorpha sp. indet. 



This coral fauna is undoubtedly the same as that in the 

 lower Noric zone of Shasta County, California, and has several 

 species in common with that fauna. 



This discovery of reef-building corals in Alaska extends 

 their range northward from 45° in the Alps, and in the Blue 

 Mountains of Oregon, to 60° N. Lat. The coral zone in Cali- 

 fornia, Oregon, Nevada, and Alaska belongs to the same hori- 

 * Bull. 208, U. S. Geol. Survey, p. 102, 1903. 



