Reviews — The Ne%v Madrid Earthquake, U.S.A. 225 



disturbance caused it to be regarded as one of the great earthquakes 

 of the world, and according to Mr. Puller it may be taken as a type, 

 exhibiting in unusual detail the geologic effects of great earth- 

 movements upon unconsolidated deposits. The area affected was in 

 the Central Mississippi Valley, including South-Eastern Missouri, 

 North-Eastern Arkansas, and Western Kentucky and Tennessee. After 

 gathering the information previously published, and calling special 

 attention to the graphic account given by Lyell, the author describes 

 many features still well preserved, among them fissures and faults, 

 the former in many cases being infilled with intruded sand (sand- 

 dikes).^ Other features comprise sunk lands, among which are sand 

 sloughs or broad and shallow troughs with ridges covered by extruded 

 sand (sand-blows) ; also certain river-swamps, and tracts with lakes. 

 Thus Eeelfoot Lake in Tennessee, which is 8 or 10 miles in 

 length and 2 or 3 in breadth, indicates a submergence of from 

 f) to about 20 feet, and rising from its waters there are still 

 numerous shattered stumps of trees that flourished prior to the 

 catastrophe. The earthquake is attributed to earth-movements 

 "associated either with the processes of folding or warping, or 

 incident to a depression and deepening of the basin ". The subject is 

 well illustrated with maps, diagrams, and pictorial views. 



Bulletin 499 (1912) contains an account of " Coal near the Black 

 Hills " on the borders of Wyoming and South Dakota, by Mr. R. W. 

 Stone. Cambria is the only place where good workable coal has been 

 found over a considerable area. It occurs in the Lakota Sandstone 

 (Cretaceous), and it is remarkable that the sedimentary strata and the 

 coal itself contain both gold and silver. In the coal the average value 

 per ton of the gold is $2*46, and of the silver |-28. The author 

 remarks that "the most plausible explanation seems to be that the 

 sands which submerged the swamp and now form the roof of the coal- 

 bed were derived in part from old gold-bearing alluvium. . . . 

 Currents which transported the sand and the grit which occur in 

 some places a few feet above the coal certainly were strong enough to 

 transport fine gold. While the sand was being deposited the gold 

 may have worked down into the underlying bog and is now found in 

 the coal". 



Bulletin 500 (1912) is on the " Geology and Coal-fields of the Lower 

 ]\ratanuska Yalley, Alaska", by Messrs. G. C. Martin and F. J". Katz. 

 The formations include (1) various schistose rocks, classed as 

 Palaeozoic, (2) greywackes, slates, and igneous rocks, classed as Early 

 Mesozoic or older, (3) Jurassic, (4) Cretaceous, (5) Tertiary, and (6) 

 Quaternary. The coal-bearing strata belong to the Chickaloon 

 formation of the Eocene, which covers the greater part of the valley 

 of the Chickaloon river, south of Castle Mountain. In thickness the 

 formation appears to be at least 2,000 feet, and it consists of shales 

 and sandstones with ironstone nodules and seams of coal, also many 

 plant-remains, chiefly leaves. Much of the coal is of high-grade 

 bituminous character. Seams occur in thickness up to about 14 feet, 

 but these are often shaly, and the thickness is usually much less. 

 The outcrops occur generally at steep angles. 



1 See also article by Dr. A. P. Pavlow, Geol. Mag., 1896, p. 49. 



DECADE V. — VOL. X. — NO. V. 15 



