WEEKS.] 
PALEONTOLOGY, PETROLOGY, AND MINERALOGY, 1901. 53 
431 Keyes (Charles R.). A schematic standard for the American 
( larboniferous. 
Am. Geol., vol. 28, pp. 299-305, fig. 1, 1901. 
Presents a general section of the Carboniferous of the Mississippi Val- 
ley and discusses its correlation with other regions. 
432- -[Review of "Geology of eastern Choctaw coal field" by 
J. A. Taff and G. I. Adams.] 
Am. Geol., vol. 28, pp. 318-319, 1901. 
433 ■ Time values of provincial Carboniferous terranes. 
Am. Jour. Sei., 4th ser., vol. 12, pp. 305-309, fig. 1, 1901. 
Discusses the time ratios of the several subdivisions <>i the Carbon- 
iferous of the Mississippi Valley region. 
434 - - Note on the correlation of the Clarinda well section with the 
schematic section of the Carboniferous. 
[owa Geol. Surv.., vol. 11, pp. 461-4(33, L901. 
Compares the well section with the general section. 
435 A dcpositional measure of unconformity. 
Abstract: Science, new ser., vol. 13, pp. 135-136, 1901. 
436 On a crinoidal horizon in the Upper Carboniferous. 
Science, new ser., vol. 13, pp. 915-916, 1001. 
Hescribes its occurrence and its bearing on the stratigraphy of the 
Mississippi Valley. 
437 Zone of maximum richness in ore bodies. 
Science, new ser., vol. 14, pp. 577-578, 1901. 
( Jontains abstracts of recent papers by Emmons and Weed. 
438 - - Horizons of Arkansas and Indian Territory coals compared 
with those of other trans-Mississippian cools. 
Eng. and Mg. Jour., vol. 71, pp. 692-693, 2 figs., 1001. 
Discusses the relations of the coal-bearing horizons of the trans-Mis- 
sissippian region. 
439 The stratigraphical location of named trans-Mississippian 
coals. 
Eng. and Mg. Jour., vol. 72, p. 198, 1901. 
Gives list of geological formations and the coals occurring in each. 
440 Contiguity of ore deposits of different generic relationships. 
Abstract: Eng. and Mg. Jour., vol. 72, pp. 597-598, 1001. 
441 Diverse origins and diverse times of formation of the lead 
and zinc deposits of the Mississippi Volley. 
Mining and Metallurgy, vol. 24, pp. 715 717, L901. (No1 - 
