448 REVIEWS 
shales are usually interbedded with the coal seams; though known to the miners as 
fire-clay, they are not very refractory. At Grand Ledge they are utilized for the 
manufacture of tile and sewer-pipe, and at Saginaw for paving brick. The shales of 
the Michigan series form a belt ten to twenty miles in width surrounding the Car- 
boniferous area in the Lower Peninsula. They are best shown at Grand Rapids, 
where they form a bed six to ten feet thick overlying the gypsum. They are suited 
for common brick manufacture, for which they are at present used. The Coldwater 
shales are extensive and important, being used in all the Portland cement plants of 
the state. For this use they have been quarried extensively at Bronson, Union City, 
and Coldwater. According to laboratory tests, these shales show the properties 
desirable in the manufacture of vitrified wares. The St. Clair shales outcrop southeast 
of East Jordan. They weather to a tenacious clay and burn to a good red color. At 
Alpena a clay shale of the Traverse (Hamilton) series is used in the manufacture of 
Portland cement, and tests prove it to be suitable for the manufacture of high-grade 
brick. 
The clays of the state are all Pleistocene, and represent three types: morainic or 
drift clays, lake clays, and river silts. ‘The morainic clays are invariably calcareous, 
while the lake clays are very frequently so. The river silts are less likely to be calca- 
reous, but are usually gritty. Morainic clays are used in the manufacture of pottery 
and brick at Ionia, Lansing, and Kalamazoo. ‘The extensive brick clay deposits near 
Detroit are lacustrine in origin, while at Rockland a lake clay furnishes slip. At 
Sebewaing, Badoxe, Croswell, and Minden City river clays are used in the manufac- 
ture of brick. 
RIES, HEINRICH, AND SMITH, EUGENE. Preliminary Report on the Clays 
of Alabama. Bulletin 6, Alabama Geol. Surv., 8vo, pp. 220, Igoo. 
This bulletin is divided into three sections. The first and third —entitled 
respectively “General Discussion of Clays” and “ Preliminary Report on the Physical 
and Chemical Properties of the Clays of Alabama”—are by Ries; the second, 
entitled “Geological Relations of the Clays of Alabama,” is by Smith. 
The first section discusses the origin, mineralogy, chemical, and physical proper- 
ties, methods of testing, mining, and preparation of clays. 
In the second section the clays of the various geologic formations of Alabama are 
described. Under the head of “Archean and Algonkian” the residual kaolins are 
discussed. A belt of mica schists with frequent pegmatite veins extends from 
Cleburne and Randolph counties through Clay and Coosa into Chilton county. In 
numerous cases the decay of the granite veins has given rise to kaolin deposits. All 
these deposits are distant from railroads, and are consequently undeveloped. 
In the area underlain by the Cambrian and Silurian rocks the clay deposits are 
the residual clays left from the decomposition of the limestones of these formations, or 
concentrations of these residual clays by redeposition in ponds and other depressions, 
or accumulations in depressions of kaolins derived from the pegmatites above men- 
tioned. The residual clays usually contain much silica and iron, and are largely used 
in the manufacture of brick. Occasionally, in the re-deposited clays, sorting has 
occurred during redeposition, and beds of very pure clay occur in consequence. 
Thick deposits of pure white clay, suitable for stoneware and pottery, are found 
in the area underlain by the sub-Carboniferous in De Kalb and Calhoun counties. 
These are extensively mined, most of the product being shipped to Chattanooga, Tenn. 
