124 On the Siudy of the Principles of Stratification. 
Gli Slatyanadls ees 25. Ran ee Soon 
7. Dark blueish-gray limestone, resembling the 3 feet 
Gunwarden limestone 1s 2... es : 
8. Disintegrated basalt with caleareous spar .. 1 foot. 
9: Compact basalts) be ee oe ee ew? SMOG 
10, Slaty marl—lowest. 
Dip south-east at an angle of 8 degrees. 
Before closing this letter, it will not be amiss to notice a few 
phenomena usually accompanying basalt in this part of. the: 
kingdom, which may in some measure serve to develop its: 
origin. Limestone is often rendered highly crystalline and unfit 
for lime, when in the vicinity of this rock, as is the case of 
No. 5 and No. 7, but not No. 3 of the foregoing section. Slate 
clay is turned into a substance like flinty slate or porcelain jas- 
per, No. 2; and coal is invariably charred when in contact with 
it. When basalt occurs in beds, its thickness varies much mere 
than that of the rocks between which it is interposed, formmg 
wedge-shaped masses rather than regular strata; and the sand- 
stone on which it reposes is changed for some depth to a brick- 
red colour; pieces of this description of soft sandstone, taken 
from below the basalt at Bamborough Castle, broke into spheri- 
cal fragments on being immersed. in water. 
I remain, sir, 
Your most obedient humble servant, 
Newcastle-upon-Tyne, July 20, 1817. N. J. Wines. 
XX. On the Advantages that may be expected to result, from’ 
the Study of the Principles of Stratification ; with Remarks 
on the proper Objects of Inquiry in this important Branch of 
Geology. By Mr.Tuomas TrEDGoLD. 
—_——. 
Men have sought to make a World from their own conceptions, and to 
draw froin their own minds all the materials which they employed; but’ 
if, instead of doing so, they had consulted experieuce and observation, 
they would have had facts, and not opinions, to reason aboat, and might 
have ultimately arrived at the knowledge of the laws which govern the 
material world.”— Bacon. 
To Mr. Tilloch. 
Sir, — im consequence of the discovery of several facts which 
tend to elucidate the principles of stratification, the science of 
Geology has acquired an additional degree ef interest and im- 
portance. Geologists have in a great measure abandoned their 
wild and fanciful speculations ;—they have begun to make ob- | 
servations, and to register facts respecting the present state of 
the surface of the earth,—and instead of inventing hypothetical 
solutions 
