were several other step-formed plains, the highest of which was estimated
at 1,200 feet, and was seen ranging at apparently the same height for 150
miles northward. All these plains have been worn into great valleys and
much denuded. The section in Diagram 3 is illustrative of the general
structure of the great Bay of St. George. At the south headland of the Bay
of St. George (near C. Three Points) the 250 plain is very extensive.

(DIAGRAM 3. SECTION OF PLAINS AT PORT DESIRE.

From East (sea level) to West (high):
Terrace 1. 100 Est.
Terrace 2. 245-255 Ba. M. Shells on surface.
Terrace 3. 330 Ba. M. Shells on surface.
Terrace 4. Not measured.)

At Port Desire (forty miles southward) I made several measurements with the
barometer of a plain, which extends along the north side of the port and
along the open coast, and which varies from 245 to 255 feet in height: this
plain abuts against the foot of a higher plain of 330 feet, which extends
also far northward along the coast, and likewise into the interior. In the
distance a higher inland platform was seen, of which I do not know the
height. In three separate places, I observed the cliff of the 245-255 feet
plain, fringed by a terrace or narrow plain estimated at about one hundred
feet in height. These plains are represented in the section Diagram 3.

In many places, even at the distance of three and four miles from the
coast, I found on the gravel-capped surface of the 245-255 feet, and of the
330 feet plain, shells of Mytilus Magellanicus, M. edulis, Patella
deaurita, and another Patella, too much worn to be identified, but
apparently similar to one found abundantly adhering to the leaves of the