5462 The American Geologist. April, i89i 
TJie Overthrust Fault* of the southern Appalachians. By C. WllXABD 
Hayes. Bulletin, G. S. A., vol. ii, pp. 141-154, with map and sections; 
Feb. 9, 1891. Two thrust faults, partly coincident with planesof strati- 
fication, are traced in the moderately bent or folded strata of the great 
Appalachian valley in northwestern Georgia and adjacent portions of 
Alabama and Tennessee, receiving names from Rome and Cartersville, 
Georgia. The Rome fault is known to extend at least 275 miles, from 
Gadsden, Alabama, northeast and north into Virginia. In the vicinity 
of Rome the extent of its overthrust is at least 4 mile*, and may be 6 or 
7 miles. The Cartersville fault or thrust-plane has an inclination 
frequently so low as 5°, and rarely more than 25°. Its maximum hori- 
zontal displacement appears to be not less than 11 miles, equalling that 
of the thrust-planes studied out by Peach and Home in the highlands 
of northwestern Scotland. Other overthrust faults are mentioned as 
mapped out by Keith a few miles northeast of Knoxville, Tennessee, 
and by Walcott in the Taconic region of New York. Among the condi- 
tions on which the production of thrust faults depends, the most import- 
ant is shown by Mr. Hayes to be the relation of the rigidity of the 
strata to the superincumbent load : and he concludes that probably the 
strata had been folded and partially eroded before the time of their 
faulting. In the discussion of this paper, Prof. W. M. Davis suggests 
that the faults may have been of post-Triassic date, long after the 
Appalachian folding which took place at the close of the Carboniferous 
period. He would attribute the lateral compression producing these 
overthrusts to the same date and causes as the monoclinal tilting and 
faulting of the Triassic beds of Pennsylvania, New Jersey, and the 
Connecticut valley. 
The structure of the Blue Ridge near Harper's Ferry. By H. R. 
Gkiger and Akthur Keith. Bulletin, G. S. A., vol. ii, pp. 155-164, 
with map and sections ; Feb. 11, 1891. Ten sections are presented, of 
which nine cross the Blue Ridge and South mountain within about ten 
miles north and south of Harper's Ferry, and one acrosses the Catoctin 
mountain about ten miles east of the Blue Ridge. The authors refer 
the sandstone here forming generally the highest part of the Blue Ridge 
and of the South and Catoctin mountains to the Silurian system, and 
they regard the structure of these ranges as synclinal, mainly in open 
normal folds, with the descending order of the strata as follows : the 
Massanutten sandstone, believed by W. B. Rogers to be the lowest of 
the series and to owe its position to the overturning of anticlinal folds ; 
the Martinsburg shale; the Shenandoah limestone, known by its fossils 
to be of Chazy-Calciferous age ; the Catoctin epidotic schist; and gran- 
ite. Fossils have been found only in the limestone. 
Note on the geological structure of the Selhirl; range. By Geobge 
M. Dawson. Bulletin. G. S. A., pp. 165-176, with a section; Feb. 12. 
1891. Seeking to connect a region which has been somewhat thor- 
oughly studied in the interior of British Columbia, with the section sur- 
veyed by McConnell across the Rocky mountains proper, or the most 
