260 W. N. LOGAN 
THE ALEUTIAN AREA 
Grewingk* was the first to announce the occurrence of beds 
of Jurassic age in Alaska. These beds were discovered at differ- 
ent places along the Alaskan Peninsula and the Aleutian Islands. 
From the distribution of these beds as mapped by Grewingk the 
Alaskan Peninsula and the Aleutian Islands must have been 
under water during Jurassic times. 
In 1872 Eichwald? described an assemblage of fossils col- 
lected from these same beds and correlated them with the 
Northern Russia beds of the same age, but put both formations 
in the Lower Cretaceous. Some fossils were collected from the 
same region by Dall in 1883. These forms were described by 
White,3? who after making a study of them and comparing them 
with Eichwald’s descriptions, decided that the latter was wrong 
in his assignment of the beds to the Cretaceous. He found them 
to be closely allied to the Jurassic of Northern Russia. One 
species, Aucella concentrica Fisher, he considers either identical 
or only a variety of the Eurasian Jurassic form of that name. 
Hyatt,‘ in speaking of these deposits, says: ‘‘ The fauna of 
the Black Hills, acknowledged to be Jurassic by everyone but 
Whiteaves, is in part apparently synchronous with that of the 
Aleutian Islands and Alaska, as described by Eichwald and 
Grewingk.”’ 
The position of these beds and the relation of the fauna with 
the northern Eurasian fauna points clearly to an Arctic-Pacific 
connection by way of the Bering waters during this epoch. More- 
over we now have an almost continuous faunal record extending 
from Alaska to southern Utah. 
Conclustons.— An examination of the above sections will show 
that the thickness of the Jura in the interior is not very great. 
An average of ten localities gives a thickness of but little over 
tRussian Kaiserl. Mineral Gesell., 1848-9. 
? Geognostisch-Paleontologische Bemerkungen iiber die Halbinsel Mangischlak 
und die Aleutschen Insel. 
3 Bull. U.S. Geol. Surv. No. 4, 1884. 
4Bull. Geol. Soc. Am., Vol. V, 1894, p. 409. 
