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Geology of St. Croix. 69 
Sometimes these valleys and the impending mountains are 
wild and picturesque in the extreme; in other cases, they are 
highly cultivated. The contrast is owing principally to the = 
ferent degrees of hardness in the rocks. 
One is at first surprised, that any portion of soil can be rekon 
on the cultivated parts of the mountains, as they are so steep that, 
in ordinary cases, it would all be washed away. It would be in 
this, but for the fact, that the cane is planted in deep trenches, 
dug horizontally along the sides of the mountains, which prevent 
in a great measure the flowing of water ; and also, that the rocks 
are continually decomposing and forming a new soil. Indeed 
this process of decomposition may every where be seen at present 
going on, in sections of roads cut through the rocks, where the 
passage from the solid, unchanged strata beneath, to the cultivated 
soil on the surface, is so gradual, that no distinct line of separa- 
tion can be Sea : 
_ A similar explanation is applicable to the different states in 
which the talus is found at the foot of the mountains. In some 
places, it is many feet deep, but thoroughly pulverized ; in others, 
it remains in the state of broken fragments, covered with so little 
soil, as not- to be susceptible of cultivation. This is strikingly 
seen at Ham’s. Bluff, which presents a stratum of ‘undecomposed 
detritus twenty-five or thirty feet in depth. » 
The thickness of this formation is at least several hundred feet. 
On the west coast, north of Sprat Hall, the strata are seen stand- 
ing side by side, in uninterrupted succession, for several rods; 
and, were it not for the gorges which break, occasionally, cbt 
continuity, the thickness might appear much greater. 
As to its age, I am not prepared to express a decided opinion. 
On the one hand, it cannot: be so low down as the older slates or 
the metamorphic rocks of Lyell; and; on the other, its composi- 
tion, structure, and high inclination, bear a striking resemblance 
to those of greywacke. I did not observe it associated with 
older rocks, except in one place, near South Gate, where a bed of 
sienite occurs, thirty or forty rods in extent. As to organic re- 
mains, though I-made diligent search, I found none ; from which 
it must at as be inferred, that, if they exist at all, they are very 
uncommon. I ought, however, to mention, that, on the road 
from Little La Grange to Punch, I discovered in this formation, 
from two to three hundred feet above the level of the sea, a bed 
