Height in feet above sea level.

Depths in fathoms.

Vertical and horizontal scale, two inches to a nautical mile. The point
marked 1,600 feet is at the foot of High Knoll; point marked 510 feet is on
the edge of Ladder Hill. The strata consist of basaltic streams.

Section left to right:

Height at the foot of High Knoll: 1,600 at top of strata.

Height on the edge of Ladder Hill: 510 at top of strata.

Bottom at coast rocky only to a depth of five or six fathoms.

30 fathoms: bottom mud and sand.

100 fathoms sloping more sharply to 250 fathoms.)

When viewing the sea-worn cliffs of Patagonia, in some parts between eight
hundred and nine hundred feet in height, and formed of horizontal tertiary
strata, which must once have extended far seaward--or again, when viewing
the lofty cliffs round many volcanic islands, in which the gentle
inclination of the lava-streams indicates the former extension of the land,
a difficulty often occurred to me, namely, how the strata could possibly
have been removed by the action of the sea at a considerable depth beneath
its surface. The section in Diagram 7, which represents the general form of
the land on the northern and leeward side of St. Helena (taken from Mr.
Seale's large model and various measurements), and of the bottom of the