118 
agricultural investigators, and it here receives a wide 
geological application. Hoyt S, Gale, in describing 
(Bull. 580L) the salines of Borax or Searles Lake, 
San Bernardino Co., California, touches on-the same 
point, and regards the preservation of potassium 
chloride in the brine of this lake-area as quite excep- 
tional. The analysis quoted on p. 294 of his paper, 
on which so much depends (see p. 311), seems to have 
gone far astray. Should we read 12-30 for the per- 
centage of potassium chloride, in place of 1-50? The 
author’s well-illustrated account of the salts crystal- 
lised in this desiccating region forms a convenient 
synopsis for students of mineralogy. Bull. 603 is of 
interest from the evidence given that the mineral oils 
north of Coalinga, California, originated in the decay 
of diatoms of Upper Cretaceous age. 
In discussing a ‘“ Gold-Platinum-Palladium Lode in 
Southern Nevada” (Bull. 620A), Adolph Knopf re- 
views the known occurrences of platinum, and points 
out that this metal may be reasonably looked for in 
copper ores, having, as Kemp suggested, migrated 
with them in solution. At the Boss Mine, in Nevada, 
the gold and platinum occur alloyed in almost 
equal quantities by weight. W. Lindgren describes 
(Bull. 601) the rich gold ores of the national mining 
district in northern Nevada, where the exceptional 
attractions of quartz ‘“‘averaging about $30,000 a ton 
in gold of a value of $10.60 an ounce” led, as recently 
as 1912, to armed alarums and excursions of the 
good old western type. A defensive searchlight has 
been kept playing on the entrance of the National 
Mine. Outside the National lode, the veins contain 
silver and antimony ores; but all the minerals are 
probably connected in depth, as products of ephemeral 
hot springs at a late stage in the eruption of Cainozoic 
(Miocene?) rhyolites. 
G. C. Matson’s description (Bull. 604) of ‘‘The 
Phosphate Deposits of Florida’’ is accompanied by 
a large coloured geological map of the State, on the 
scale of 1:1,000,000. The most interesting feature 
of this is the famous Florida East Coast Railroad, 
which steps from isle to isle of coral, and ends on 
the Pleistocene oolite of Key West. The marine con- 
cretionary phosphates are believed (p. 64) to have 
originated from the remains of plants and animals, 
while the fluviatile Bone Valley Gravel, in which 
teeth of Mastodon and other vertebrate remains occur, 
is held to have received its calcium phosphate from 
the detritus of the underlying marine bedrock. 
Among several publications that indicate the rapid 
progress of surveying in the difficult regions of 
Alaska, we note Bulletin 587, by G. C. Martin, B. L. 
Johnson, and U. S. Grant, on the Kenai Peninsula. 
Cainozoic coal-seams occur near the sea; but they 
seem unlikely to compete with the coals of higher 
grade available on the Pacific coast. It is of interest 
to find (p. 52) a series of “green scoriaceous and 
ellipsoidal lavas” of Triassic age overlain by radio- 
larian cherts. Once more we see that a particular 
marine condition has brought about the formation of 
these two dissimilar rock-types, though the clear 
evidence of succession in this case prevents our 
ascribing the abundance of radiolarians to the emana- 
tion of silica from the lavas. The detailed work by 
C. W. Wright on Copper Mountain and Kasaan 
Peninsula (Prof. Paper 87) includes well-illustrated 
observations on contact-metamorphism. Some of the 
aplite veins (p. 81) contain as much as g per cent. 
of primary calcite, a mineral that has already taken 
its place as an original constituent of igneous rocks. 
S. R. Capps (ibid., 95D) traces the volcanic ash layer 
of the Yukon basin to a “centre of dispersion,"’ by 
no means central, north of Mount Logan. At this 
point the deposit is 300 ft. thick, fading away to a 
NO. 2450, VOL. 98] 
“NATURE 
[OcToBER 12, 1916 
foot in about 150 miles to eastward. The layer is 
traceable over 140,000 square miles, and, from the 
thickness of peat above it on the White River, is 
ascribed to an eruption that took place on the north 
of the Mount St. Elias region about 1400 years ago. 
The report by A. H. Brooksy who superintends the 
surveying work in Alaska, on the mineral resources 
of the region in 1914 (Bulletin 622) includes an un- 
favourable judgment on some of the coals from the 
point of view of the Navy Department; the coal of 
the Matanuska field, however, is regarded as of 
excellent steaming quality, and the progress of gold- 
mining, the great industry of Alaska, may possibly 
open up this field. 
W. B. Clark and M. W. Twitchell have written a 
monograph on ‘‘The Mesozoic and Cenozoic Echino- 
dermata of the United States’’ (Monograph 
liv.), illustrated with 108 plates of drawings and direct 
photographs. While the genera are for the most part 
of world-wide occurrence, few of the familiar 
European species are found in American deposits. 
F. W. Clarke and W. C. Wheeler (Prof. Paper goL) 
follow up their work on the composition of crinoid 
skeletons by an examination of the hard parts of 
other recent echinoderms. Magnesium carbonate is 
found in these also; the quantity is large in tropical 
forms as compared with those from cold waters, and 
may reach 14 per cent. The authors conclude that a 
rock formed from any kind of echinoderm ‘will have 
the composition of a moderately magnesian lime- 
stone.’’ As previous workers have pointed out, the 
calcium carbonate of echinoderms is always in the 
calcite form. 
Mineralogists and chemists will alike appreciate 
F. W. Clarke’s essay on “‘The Constitution of the 
Natural Silicates’’ (Bull. 588), in which consideration 
is given to their alteration-products, as suggesting the 
structure of the molecule of the original mineral. The 
treatment of spodumene (p. 98) serves as an interest- 
ing example, and leads on to new interpretations of 
the pyroxenes and the amphiboles, which are worked 
out as mixtures of orthosilicates and trisilicates, while 
wollastonite and pectolite, which are easily decom- 
posed by dilute acids, remain isolated as metasilicates. 
Whitman Cross (Prof. Paper 88) enlarges our im- 
perfect knowledge of ‘‘The Lavas of Hawaii and 
their Relations,” covering the Hawaian Islands as a 
whole. The mountain-chain of which these are the 
unsubmerged peaks extends for 1800 miles in a north- 
north-westerly direction. The rock-types offer no sup- 
port to the suggestion of a distinctively Pacific group 
of igneous rocks, or a group produced under Pacific 
conditions, and the alkalic and calcic rocks of Rosen- 
busch occur in the islands (p. 86) as derivatives from 
a common source. The author doubts (p. 90) Daly’s 
view that limestone has had an influence in promot- 
ing the occurrence of the types rich in alkalis. His 
visit to the islands in 1902 enables him to review his 
specimens as parts of some of the most striking vol- 
canic landscapes in the world. 
The twenty-third volume of the Iowa Geological 
Survey (1914) consists of O. P. Hay’s monograph on 
“The Pleistocene Mammals of Iowa,” the remains 
being found in interglacial beds. The Aftonian stage, 
following the. first Glacial or Nebraskan stage, is 
especially the horizon of Mylodon, in North America, 
and of the last North American Camelidz. The 
memoir is fully illustrated. R. S. Lull reviews 
(American Journal of Science, vol. xl., 1915, Pp. 319) 
“The Mammals and Horned Dinosaurs of the Lance 
Formation of Niobrara County, Wyoming,” and 
shows that mammalian remains, including through- 
out the older multituberculate types, are found in 
almost all the beds that contain Ceratopsia. The tri- 
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