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Mr. Weaver on the 
presented is vertical, but to the east of the projecting ledge we may 
'observe, at low water, an horizontal section also, in which the beds 
form curves converging one within another ; whence it would 
appear that the series constituted at one time great lenticular masses, 
composed of concentric lamellar concretions, enveloped in the 
general body. I consider these as instructive appearances, tending 
to explain many of the flexures in strata, the limits of which we 
have not an opportunity of following with the eye ; (§67.) 
The beds on the western side of this inlet become gradually 
mixed with quartz, and at length pass into quartz rock ; and at the 
very point projecting toward the sea, we meet with a body of fine 
compact greenstone porphyry, flanked on either side by quartz 
rock, which also on the southern side forms high peaky rocks, 
standing out into the sea. The porphyry itself is visible only at low 
water, being nearly covered by the sea and inaccessible at flood tide. 
It appears to range and dip conformably with the quartz rock, 
and to form a bed eight fathoms wide in the broadest part, which 
is in the south-eastern quarter, in which direction it is soon con- 
cealed by the sea ; but in its progress to the north-west it separates 
into two branches, each three to four fathoms wide, and the inter- 
val between them is occupied by quartz rock, which they probably 
inclose, coinciding again to the north-west. This, however, cannot 
be determined with precision, as the continued line of junction is 
not visible, although the porphyry is perceptible for thirty or forty 
fathoms farther to the north-west, encumbered and partly concealed 
by loose masses of rock, beneath which and the sea it at length 
disappears. 
To the west of this projecting point is another small inlet, in the 
eastern quarter of which the rocks range 40° north of west and 
south of east, dipping 70° toward the south-west; but in proceed- 
