REVIEWS 447 
are located along an approximately north and south line which extends from the 
Hampton variegated quarries on the north, through the North Bend, Middle Granville, 
Granville red and the Slateville red and green quarries, and the purple and green 
quarries of Salem, Shushan and Cambridge. The East Whitehall (Hatch Hill) quar- 
ries are west of the northern end of this belt. 
The red and green slates are cut to size at the mills. The mottled slates, being 
unsalable in the natural condition, are “ marbleized,’ an enamel being applied to 
give imitations of marbles,etc. The refuse from the slate mills is ground and used as 
a pigment. 
Peck, F. B. Preliminary Notes on the Occurrence of Serpentine and Talc at 
Easton, Pa. Annals N. Y. Acad. Sci., Vol. XIII, pp. 419-430, Pl. 16, 
Figs. 4, 5, 1901, 
Chestnut Hill is a pre-Cambrian outlier near Easton, composed of a dense horn- 
blende gneiss with interstratified beds of carbonates. These beds, five to thirty feet 
thick, consist of pink calcite, gray dolomite, or a mixture of the two, Along a series 
of thrust faults great shearing has occurred. Hornblende (usually tremolite), phlogo- 
pite, and occasionally pyroxene, occur so abundantly in these beds as locally to 
replace all or most of the carbonates. The calcite dolomite beds shear to a slaty, 
foliated talcose mass consisting of a mixture of talc, tremolite, serpentine, or without 
shearing, become changed to beds of nearly pure white tremolite. The phlogopite, 
which is developed locally in large quantities, alters quite uniformly to serpentine and 
constitutes the chief source of that material in the eastern quarries. One particularly 
attractive phase of the material quarried consists of numerous rose-colored dolomite 
crystals scattered through a mass of serpentine. 
Ries, HEINRICH. The Origin of Kaolin. Trans. Amer. Ceramic Soc., Vol. 
II, 1900. 
The author defines the kaolins as “those clays which are residual] in their nature, 
and which’ burn to a sufficiently white color to be used in the manufacture of white 
earthenware.” Thus restricted, two different modes of origin of kaolins are discussed. 
In most cases kaolin has been derived from the decomposition of a highly feldspathic 
rock, through the action of surface agencies. Von Buch, Daubree, and Collins have, 
however, pointed out that acid vapors (particularly that of hydrofluoric acid) coming 
up from below, may decompose feldspar and yield kaolin. Deep deposits, especially 
if containing unaltered sulphide minerals, may have been formed in this way, and the 
kaolins of Cornwall, England, and Zittlitz, Bohemia, have been undoubtedly so 
formed. All the commercially valuable deposits of the United States, however, are of 
the other type, being due to ordinary weathering. 
Ries, HEINRICH. Clays and Shales of Michigan. Geol. Surv. of Mich., 
Vola VilliijePty 1.) 8v0,.pp07,0bl.1-1Ve Migs1—6, Lo0o. 
That part of the work relating specifically to Michigan is preceded by chapters 
on the origin, properties, uses, and methods of testing clays and shales. Following 
these are discussions of the shales and clays of Michigan. 
The important shale horizons of the state are four: the Coal-measure shales, the 
Michigan series, the Coldwater shales, and the St. Clair shales. The Coal-measure 
