Tae 
. 
Geological Results of the Earth’s Contraction. 89 
It should be remarked, that in the engin. summary the 
causes alluded to are not presented ‘as only source of the 
effects enumerated, though a haat anit sufficient source. 
The causes have acted conjointly with the wide-spread agency 
of water, yet they may have been less dependent on the latter for 
many results, than has often been urged. We mention no authori- 
ties for any of the conclusions stated, as they are already given, as 
ar as known to the author, in the previous articles alluded to. 
General Review of the Consequences of the Earth’s Cooling. 
L. Solidification of the surface after the fluid material had lost 
its perfect fluidity. 
a. The e change inconceivably slow, and hence the rock formed hav- 
ing a coarsely crystalline texture :—the subsequent progress of solidifi- 
cation beneath the crust still more gradual, and sacesiore producing at 
result of a single immeasurably prolonged operation. 
. Hence, probably, a general uniformity in the crystalline structure, 
sufficient to give the crust t apparently two directions of easiest fractu 
whose mean courses are .b, W. and N.E. b. ; yet varying much, 
ee ae a SS A 
* We add here a reference to the Horm np on a io 9.7 by W. 
ingen 4 sth 
Sharpe, Esq., in the Quart. Jour. Geol. Soc 74-105. 
See also this ‘Journal, last volu ork p- aia p- 110, in nine ip 
See also on the effects of cooling, De la Beche’s Report on Cosmin evon 
et, 8vo, 4 ndon, 1839, 3, and elsewhere. 
W. Somers 
t Long sustained heat of a requisite and searcely varying temperature, | is the 
essential circumstance demanded for the distinct crystallization 0 of most oe 
from fusio It is well known that lava stream ming incrusted ov 
. ling. tt pass to the cold state too ‘rapidly or in a 
larly, for a coarse crystallization of all the several ingredi of ther eve ce 
peter the absolute necessity of the dom prod state ae YS. h mace Sete 
Where, that a granite-like structure = . om produce 
cept in its central mass of lavas wl finally cool, pe oat from ihe air ee 
thick beds of non-conducting r falas speci 
ti 
We remark farther, that a long- -continued BO cis bins ee te 
a condition of the greatest peg sngrent ed eae ; 
i ur 
condition which the or of nature has established mn ig i a structure, 
here the most complex compositions take place. And z en the ogy ete St 
Earent tn spenitic cases ie, nec at hi neg a aicat’ chen poallgorie will 
temperature are at hand, we ma ict t 2 jcaei” “Phe reason 
aC 
for this is obvious, if we consider that with difference se eoleg aa she 
difference of size, and difference gf Stra ae power both cohesive a m . 
+ Well illustrated on the surface of the moon, as also are many of the points here 
; mentioned, (ii, 335.) See Beer and adagiers cha rts. 
Sxconp Pans, Vol. IV, No, 10.—July, 1847. 12 
