96 The American Geologist. February, i899 
San Juan valley near Castillo. In late Tertiary or post-Tertiary 
time the isthmus was elevated at least 300 feet, and deeply dissected. 
Following the elevation was a renewal of volcanic activity. A series 
of vents on the Pacific side and their ejecta built a dam across the 
outlet of the gulf, thereby forming the lake basin. As this dam in- 
creased in hight the waters behind it were raised until they over- 
topped the contiental divide and escaped to the Atlantic, forming 
the present San Juan river. The region has suffered a recent depres- 
sion by which the rivers were drowned and the estuaries thus formed 
have since been silted up. 
" T/w Faunas of the Upper Ordovician m the Lake Cham- 
plain Valleys^' by Theodore G. White, of Columbia Uni- 
versity. Results of a detailed study' of the consecutive faunas con- 
tained in each stratum at numerous localities throughout the length 
of the valley. A complete section is afforded from the base of the 
Black River formation through the Trenton and terminating in the 
Utica. Species hitherto reported only from Canadian localities are 
found associated with those characteristic of the Trenton Falls type- 
province, showing the Champlain connection of Ordovician seas. 
Several zones characterized by restricted species are located, and also 
"conglomeratic zones." The fauna is very abundant and supplies a 
basis cf comparison for similar detail study from other provinces. 
The occurrence of the Hudson River and Oneida groups in the re- 
gion is questioned. 
I. C. Russell, of Michigan University, gave a preliminary account 
of the p^eneral geology of the Cascade mountains in northern Wash- 
ington, based on a reconnaissance made during the past season. The 
region treated of extends about sixty miles east and west along the 
Northern Pacific railroad and one hundred and twenty miles north- 
ward to the Canadian boundary. Carboniferous and Triassic rocks 
are exposed which the author divides into the Similkameen and the 
Ventura systems. The extensive Tertiary outcrops are divided into 
the Snoqualane slate, Winthrop sandstone. Camus sandstone. Swank 
sandstone. Roslyn sandstone, and the Ellensburg sandstone. There 
is an abundance of fossil leaves. Moraines and valley gravels consti- 
tute the Pleistocene beds. As to eruptive rocks, granite, andesyte 
and acid and basic dikes occur, but basalt is generally absent. The 
paper then discussed the laccolithic domes, the folds and faults, the 
Cascade peneplain and the Cascade plateau with its dissection. There 
are indications of several ancient glaciers on both sides of the Cas- 
cade range, but the northern drift is absent. Along the Columbia. 
Snake and Spokane rivers there are great terraces, due to climatic 
changes, but there is no evidence of recent submergence. Glaciers 
are now to be found in the Wenatchee mountains and the Cascades. 
Coal, gold, copper, iron, building stones, clays, etc., are found in the 
region. 
" The Geology and Archeology of California,"' by W J McGee, 
of the Bereau of Ethnology, and W. H. Holmes, of the National 
