OcToBER 12, 1916] 
GEOLOGICAL WORK IN THE UNITED 
STATES. 
{pHs United States Geological Survey, under the 
directorship of G. Otis Smith, continues to dis- 
cuss theoretical and practical problems from the most 
liberal point of view. T. Nelson Dale’s account 
(Bulletin 589) of ‘Marble and Dolomite of Eastern 
Vermont”’ directs attention to a rose-coloured man- 
ganiferous calcite marble, “alternating in very small 
beds with equally small beds of fine-textured white 
dolomite." The author refers to his previous dis- 
cussion of dolomite (Bull. 521), and suggests that the 
dolomite layers were precipitated inorganically, while 
NATURE 
117 
that all the Cretaceous coal-seams of the region, from 
Dakota times onward, were deposited on the mar- 
gins and sometimes towards the centre of a single 
gradually subsiding shallow basin, which (p. 57) 
reached from the Gulf of Mexico to the Arctic Ocean 
and from Utah to the Mississippi. The orogenic 
| movement of Eocene times resuscitated the Rocky 
| Mountain mass, 
the pink calcite layers received their manganese from ; 
organisms. Both the hard and soft parts of molluscs 
may contain appreciable ‘percentages of manganese ; 
but why should rose-coloured marbles be comparatively 
rare? The examples from Vermont lose their colour 
if used for external decoration. 
In Monograph Ixiii. F, Leverett and F. B. Taylor 
provide a detailed description of the ‘Pleistocene of 
Indiana and Michigan and the History of the Great 
Lakes." They conclude that the changes and de- 
formations of shore-lines in this region may be due 
to crust-creep, as well as to alterations in the ice- 
burden, but tp: 333) that the land is at present stable. 
The long eskers, formed during glacier-retreat in 
channels bounded by the ice, are excellently illustrated | 
in the maps (see, for example, plate viii.), and the 
elaborate nature of the survey may be judged from 
the folded sheet, plate vii., where the moraines of the 
peninsula between Lake Michigan and Lake Hudson, 
with the lacustrine clays deposited behind them, are 
shown over a region measuring 300 by 200 miles. 
The Michigan Geological Survey has furnished im- 
portant data for this memoir. 
Bulletin 600 is a popular guide to the geology and 
scenery of ‘The Glacier National Park,’ Montana. 
The Continental Divide runs through’ the park, among 
peaks carved out of stratified rocks, which are from 
gooo to 10,000 ft. in height, and some 6000 ft. above 
the valley-floors. A few residual glaciers ‘still linger 
in the cirques. The region was originally purchased 
from the reservation of the Blackfeet Indians, in 
order to encourage copper-mining. The mines having 
proved unprofitable, the beauty of the country was 
represented to Congress in 1910 (Fig. 1). A good 
map accompanies this bulletin; but those who become 
interested in the folding and overthrusting and subse- 
quent dissection of the strata of the park may like 
to learn more about their geological age than that 
they “are very, very old.” 
In North Park, Colorado (Bull. 596), lenticular 
masses of coal of extraordinary thickness occur in 
Upper Cretaceous or early Cainozoic strata. ‘These 
coals may be 20, 35, or even 53 ft. thick, and are 
referred by A. L. Beekly (p. 94) to local marsh-areas, 
unconnected with one another, which encouraged 
rapid accumulation of vegetable or other organic 
matter. North Park is unfortunately bounded by a 
ring of mountains, away from trade-routes, and the 
remarkable cleanness of the coal is likely to prove 
its chief recommendation. 
W. W. Attwood (Prof. Paper 95B) records and illus- 
trates a’rather widely spredd glacial boulder-clay of 
Eocene age in south-western Colorado. ‘In a review 
of recorded ‘“‘ice-ages,”’ which excludes the evidences of 
mere valley-glaciers,| the author finds no parallel with 
the Colorado instance, unless in the Eocene of North 
Italy. W. T. Lee (ibid., 95C) provides a possible 
source of the Eocene ice-flow in a review of the 
‘Relation of the Cretaceous Formations to the Rocky 
Mountains in Colorado and New Mexico.” He urges 
NO. 2450, VOL. 98] 
which had been worn down and 
buried beneath these Cretaceous strata. Hence the 
beds which contain conglomerates derived from the 
newly raised mountains must all be regarded as of 
Cainozoic age. The folding experienced by the coal- 
bearing strata during the uplift is well-seen in the 
illustrations from Utah in Bulletin s581E. 
From Nevada (Prof. Paper 95A) W. B. Hicks 
Fic. 1.—St. Mary Lake and Red Eagle Mountain, GlacierNational Park, 
Montana, 
draws interesting conclusions as to the apparent dis- 
appearance of potassium from the brines and saline 
deposits of the desert-basin regions. High percentages 
of potassium are obtained by boiling the muds of 
Columbus Marsh with water, and the author believes 
(p. 9) that these muds have withdrawn potash from 
percolating solutions, holding it in virtue of their 
colloids or in a weak chemical combination. Only a 
small proportion of the potash can be referred to 
extraction from the mud-forming minerals, and (p. 8) 
“the potash content of the muds is roughly constant 
without regard to the character of the material,” i.e. 
whether this is sand or clay. The retention of potash 
| by soil-particles has, of course, been discussed by 
