Review of Recent GeohxjicnJ Lllerdf.ure. 213 
of the sources of such stone, partly boulders and cobbles of the glacial 
and modified drift and partly quarries. The plates illustrate eskers, 
morainic boulder belts, residual boulder pavements on the seashore 
where clifis of till are being washed away, and the contiguous coarse 
shingle beaches, besides views of trap dikes in Brighton and Somerville. 
Mr. J. Edward Spurr, in jjages 3i3-455, with plates xxv-xxxiv^ and 
figures 42-47, presents an excellent report on the "Economic Geology 
of the Mercur Mining District, Utah," with an introduction by S. F. 
Emmons. From all the mining districts of theOquirrh mountains, first 
worked in 1869, it is estimated that, up to Jan. 1, 1894, more than $50,- 
000,000 of gold and silver had been obtained. In 1890 the remarkable 
Gold ledge of the Mercur district, in these mountains, was discovered. 
The ore-bearing horizon is in the Lower Carboniferous limestones. Two 
distinct periods of mineralization produced, first, the Silver ledge, car- 
rying silver with some antimony and copper, but no gold: and, at an 
undetermined later time, the Gold ledge, about 100 feet higher, which 
is a bed of decomposed limestone and shale, carrying realgar and cinna- 
bar, with a low but comparatively uniform percentage of gold, but no 
silver. In both periods the ores were deposited mainly in the i^orous or 
brecciated zone along the lower contact of intrusive porphyry sheets. 
Mr. Spurr thinks that the minerals of the Silver ledge were pressed out 
of the cooling porphyry with the included water and brought to their 
present position in aqueous solution; but that the subsequent minerali- 
zation of the Gold ledge was due to f umarolic vapors ascending from 
some body of igneous rock which did not reach the surface. 
Mr. Frederick Haynes Newell, in pages 457-533, with plates xxxv- 
XXXIX, and figures 48 .57, treats of "The Puljlic Lands and their Water 
Supply;" and the final paper of this volume, in pages 535-588, with 
plates xL-xLii, and figures 58-65, is by the late Mr. Robert Hay, on the 
"Water Resources of a Portion of the Great Plains." One of the maps 
of Mr. Newell's paper shows, for the western half of the United States, 
the areas of forest (about 15 per cent.); of woodlands having a sparse 
growth of timber (17 p^r cent): of irrigated and improved lands (7.33 per 
ceiit.); and of treeless country (61 per cent.). More than three-fourths of 
the treeless portion are rated as grazing lands: and only seven per cent, 
of all as deaert. The district carefully examined and here reported by 
Mr. Hay is a north to south belt, in southwestern Nebraska, western 
Kansas, and eastern Colorado. The topography, hydrography, and ge- 
ology, are described with relation to irrigation. 
Volumea III and IV. — For the year 1894, here reported, the metallic 
products of the United States had a value of $218,168,788: and our non 
metallic mineral products amounted to $308,486,774. With the addition 
of a million dollars for estimated mineral products not specified in the 
tabulation, the total is $527,655,562, being over a thousand times the ex- 
penditure, during that year, for the United States topographical and geo- 
logical survays. Values of the production of some of the larger items of 
the list were as follows: Bituminous coal, $107,653,501; anthracite coal, 
$78,488,063: pig iron, $65,007,247; silver, $64,000,000; gold, $.39,500,000: 
