122 
The American Geologist August, L903 
canic lapilli, with occasional beds of coarse gravel, especially near the 
bases of the bordering mountain-." The thickness of the Payette lake 
deposits, according to Lindgren, exceed- 1.000 feet in the vicinity of 
Boise, the capital of Idaho. Later, in the Pliocene period, while the 
principal lava eruptions were taking place, a smaller lake, the immedi- 
ate successor of lake Payette, remained in the southwest part of the 
state, called lake Idaho by Cope. 
Basaltic lava flows cover an area of about 20.000 square miles in this 
basin, having thus about a tenth as great extent as the vast lava field 
cut through by the Columbia river. In the Snake river canyon, below 
Shoshone falls, nearly 700 feet of lava in horizontal sheets are exposed, 
hut its aggregate total thickness has not been determined. Generally 
the various sheets of the lava, representing successive eruptions, are 
"relatively thin, averaging perhaps 50 to 80 feet, and widely extended." 
Sir Archibald Geikie. when traveling in this country in 1879, after 
seeing these Snake river plains of lava, attributed them to fissure erup- 
tions. This view, however, is not favored by Russell, who in this re- 
port presents a very convincing account of his observations, showing 
that the lava issued from many small craters on the basin plain and in 
the lateral valleys of the inclosing mountains. The eruptions began 
probably in Miocene times, and continued, interruptedly, until only a 
few centuries ago. 
Professor Russell concludes that the surface water supply is cap- 
ahle of two or three times its present utilization ; that the entire sum- 
mer flow of all the streams reaching these arid plains can be em- 
ployed for irrigation; that storage reservoirs should be constructed; 
that test wells should be drilled to pass through the lava beds, into the 
underlying fluvial and lacustrine sands and clays, in the hope of ob- 
taining artesian water ; and that the control of the water supplies, both 
for irrigation and domestic uses, should be under the direction of a 
competent engineer. w. u. 
Studicii uber das N ordbaltische Silurgebiet, I. vox Carl Wiman [Bull. 
Geol. Instit. of Upsala, No. II. Vol. VI, Part I, 1902.] 
This first study (on the Cambrian) is based on the remains found 
in the Olenellus sandstone, the Obolus sandstone and the Ceratopyge 
shale. 
A full account of the literature of the subject is given, even back to 
the time of Laurentius Roberg (17151 and onward from then. 
The mode of occurrence of the rocks is given — first, in the original 
ledges, then as loo^e block--, then as they are found in the morains, then 
the occurrences in the gravel ridges or ases ("osars"), then as they are 
found in the glacial clay, and finally as rolled fragments on the shore 
of the Baltic sea. The treatment is thus very full. 
The Olenellus sandstone -how- various phases; a predominant one is 
a" bituminous sandstone; many fragments are conglomeritic and hold 
concretions of phosphate of lime. A good many fossils have been found 
