1868. | Geology and Palzontology. 99 
the Rev. Mr. Timins, contains the results of nearly one hundred 
analyses of the rocks occurring in that range. They comprise the 
following varieties: (1) Lava and Volcanic Ash overflowing, or 
interstratified with, the Black Shale; (2) Eruptive rocks of the 
Hollybush Sandstone; (3) Shales; (4) Bedded Traps, Lavas, and 
Felstones of the Herefordshire Beacon ; (5) Felstones north of the 
Herefordshire Beacon; (6) Quartzo-felspathie veins; (7) Trisili- 
cated Felspathic veins ; (8) Felspathico-hornblendic rocks ; and (9) 
Intrusive Traps. Some of the author’s conclusions are of general 
interest, especially : that the relative proportions of the several bases 
often characterize particular localities; that the chemical composi- 
tion of the eruptive rocks does not vary according to their age; 
that the atomic proportion of the silica to the bases appears to be 
highest in the largest masses of trap (but this law, though very 
general, is not invariable) ; that in the same masses of trap there is 
an appreciable increase in the silica towards their centres; that 
the primary source of all the trap-rocks in the Malvern Hills was 
nearly a bisilicate. There are many other important inferences 
which we have no space to mention, and, indeed, this paper requires 
a most careful study to be properly understood or appreciated. 
Mr. Townsend M. Hall’s paper on the Relative Distribution of 
Fossils throughout the North Devon series, contains a valuable 
table showing the range of the species in the fossiliferous groups, 
both geologically and geographically. 
In a paper on the sources of the materials composing the White 
Clays of the Lower Tertiaries, Mr. George Maw advocates their 
derivation from the chalk, by the gradual solution of the calcareous 
matter, the aluminous and siliceous portions being left, and forming 
the white clays in question. It has been generally considered that 
these clays have, in many instances at least, been derived from the 
decomposed felspar of granite; but Mr. Maw points out that 
Kaolin, which is the result of the decomposition of felspar, is per- 
fectly implastic,—a character entirely opposed to that of the white 
Tertiary clays. An important chemical fact bearimg upon this 
matter is, that the clays in question contain the alumina in a larger 
proportion to the silica than felspar would afford. Many other 
facts are urged by Mr. Maw in support of his theory, and he gives 
numerous analyses of clays, chalk, and chalk-marl, made chiefly by 
Dr. Voelcker, Prof. Way, and Mr. C. D. Blake, which support his 
statements respecting their chemical composition. 
The last paper in this number which we have space to notice 
is one “On the Structure of the Postglacial Deposits of the South- 
east of England,” by Mr. 8. V. Wood, jun., in which the author 
gives an epitome of the results arrived at by him after a survey of 
the region mentioned, which results, and the maps and sections on 
which they are founded, are given fully in a manuscript memoir 
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