The elevatory movement, and the eating-back power of the sea during the periods of rest, have been equable over long lines of coast; for I was astonished to find that the step-like plains stand at nearly corresponding heights at far distant points.

The lowest plain is 90 feet high; and the highest, which I ascended near the coast, is 950 feet; and of this only relics are left in the form of flat gravel-capped hills.

The upper plain of Santa Cruz slopes up to a height of 3000 feet at the foot of the Cordillera.

I have said that within the period of existing sea-shells, Patagonia has been upraised 300 to 400 feet: I may add, that within the period when icebergs transported boulders over the upper plain of Santa Cruz, the elevation has been at least 1500 feet.

Nor has Patagonia been affected only by upward movements: the extinct tertiary shells from Port St.Julian and Santa Cruz cannot have lived, according to Professor E.Forbes, in a greater depth of water than from 40 to 250 feet; but they are now covered with sea-deposited strata from 800 to 1000 feet in thickness: hence the bed of the sea, on which these shells once lived, must have sunk downwards several hundred feet, to allow of the accumulation of the superincumbent strata.