GLEANINGS IN SCIENCE. 
VOL. I.] 
JANUARY I, 1829. 
[no. r. 
I— ON THE CONSOLIDATION OF THE STRATA OF 1 EARTH. 
By Sir James Hall, Bart. F. R. S. Loud. & Edin 
[From Transactions It. S. Ed. Vol. A".] 
The public attention, animated by scientific controversy, has of 1; te years been 
much directed to Geological subjects ; and t he certainty of many important facts, 
has in consequence been ascertained beyond dispute, which were ormerly un- 
known, or at least involved in such obscurity, that no person could Vive ventured 
to assert them, without being charged with extravagance- But though, no doubt, 
many branches of this science still remain to he investigated, such inquiries may 
now he said to have acquired a considerable degree of consistency and interest, 
from the substantial basis upon which they have been found to rest. 
Thus, in the present day, it is universally admitted^ that a great } t, I believe, 
in point of bulk, by far the greatest part, of the solid rock which • istitutes the 
external mass of our globe, is stratified : that these strata, or at lea a considera- 
ble portion of them, have at one period consisted of a loo.se assemblage of sand and 
gravel, broken from rocks of still higher antiquity: that these fragments are infi- 
nitely various in quality, in hulk, and inform ; some retaining their t iginal sharp- 
ness^ others rounded and polished by agitation in the water : that tin se beds alter- 
nate with others of limestone, composed, in a great measure, of the shells of sea-fish, 
which shells are also occasionally scattered through the other strata- So that on 
the whole, it seems to be ascertained to the satisfaction of all parties in geology, 
that the strata, — those, at least, of later formation, — have once constituted collec- 
tions of incoherent parts. And it is further admitted, that these bed have under- 
gone various remarkable changes, some chemical, some mechanical. 
The chemical changes consist in the consolidation of these loose as emblages into 
their present state of rock, passing, in that transition, through bourn less varieties, 
in point of flexibility and toughness, and occasional brittleness. T ue mechanical 
revolutions are no less remarkable, principally in the change of the strata. to their 
present contorted shape, and elevated position, often many thousand feet above the 
surface of the sea ; though there is full reason to, believe that they all once lay in 
a horizontal position at its bottom. 
I have said that the greatest part of the crust of our habitable globe seems un- 
questionably to be stratified, and produced from detritus or fragmented materials. 
The other portion, though probably the least hi bulk, is, generally, the most con- 
spicu'ous, owing to its durability, elevation, and picturesque beauty. This kind of 
rock is contrasted with the former class, particularly in its negative qualities ; in 
being, according to some geologists, altoget her devoid of stratification in the gene- 
lio.;d of Edinlurgh, in Arthhr’s Se.it, Salisbury Craigs, ami in Coretorphinc Hill. 
It is decidedly posterior to the stratified class, of which it. penetrates the crevices at 
i in the form of dykes or veins, like stucco cast in a mould ; frequently also 
lodging between the strata in vast shapeless masses. 
As ! lie rock in question never fails to preserve this quality of universal and per- 
fect crystallisation, I heartily concur with Dr. Hote in bestowing upon it the ge- 
neral name of Crystallite, under which are comprehended all substances of this kind 
including not only Whinstoue and Basalt, but also Porphyry, Granite, andSieuite 
of every description. 
