380 THE JOURNAL OF GEOLOGY. 
geologic history, and one extending all over the northern hemi- . 
sphere. But it becomes probable that while Eurasia was sink- 
ing, North America was rising, and that the eastward connection 
with European waters was cut off, for with the Kimmeridge there 
came in a fauna that no longer had any affinities with the cen- 
tral European, but rather with the Russian. This fauna has 
been described in the above mentioned papers by F. B. Meek, 
Professor A. Hyatt and the writer, from the Mariposa formation — 
of the Gold Belt of California, also by Professor Nikitin* from 
San Luis Potosi in Mexico. 
This type is characterized by the presence of Cardioceras of 
the group C. alternans and Aucella allied to A. pallasi and A. 
bronnt. 
There was, therefore, an elevation of a large part of America 
and also a transgression of the Boreal or Russian sea along the 
west coast as far as Mexico. This movement was correlative 
with the great Jura transgression of Eurasia. 
It is a remarkable fact that this same fauna is found in the 
Spiti shales on the north side of the Himalaya Mountains while 
the Upper Jura of Kutch on the south side is of decidedly cen- 
tral European character. Neumayr? considers the Himalayan 
Jura a southward prolongation of the Boreal sea and the Kutch 
formation a prolongation of the central Mediterranean which 
also sent down a long gulf to Mombassa on the east coast of 
Africa. These African and Indian waters were separated from 
the western American by the ancient Australo-Asian continent, 
over which no marine Jura occurred, but widespread fresh-water 
deposits with Jurassic plants. Remains of this continent are 
still seen in Australia, New Zealand, and the submarine plateau 
on which are the islands that separate the Pacific from the Indian 
Ocean. 
During all this time the Upper Jura of South America, as 
described by Dr. O. Behrendsen,3 retained its central European 
* Neues Jahrb. Min. Geol. und Pal., Band 2, 1890, p. 273. 
? Geographische Verbreitung der Juraformation, pp. 109-117. 
3Zeitschr. Deutsch. Geol. Gesell., 1891, pp. 369-420, and 1892, pp. I-42. 
