that portion of these countries west of the Cascades. At Shoalwater Bay, for instance, where the action of the surf has undermined large portions of the bluff shore, breaking it off, there are, exposed to the eye of any observer, vertical sections of sedimentary deposit one hundred feet above the present sea-level. Mixed with this deposit, and sometimes occurring in beds, are vast numbers of sea-shells, of the kinds now common to our oceans. The presence of oyster, clam, and other shells, only found in shallow water; as also of trunks of trees, leaves, seeds, and cones, — their forms preserved unbroken, — proves these fossils to have been deposited quietly in water of no great depth, and to have remained undisturbed since. Granting this apparent fact, the waters in which they were deposited must have stood more than a hundred feet higher than the present level of the ocean, or enough higher than the highest of these deposits to have sufficiently covered them.
Mr. Condon’s theory, to which reference has already been made, supposes what is now the Wallamet Valley to have been the basin of a large body of water, to which, in an article in the Overland Monthly, of November, 1871, he gives the name of the Wallamet Sound. The conclusion of that article has this interesting summing up:
"And now, with our amended theory in mind, as a measuring-rod, let us retrace our steps to the lower country, — the Wallamet Sound of the olden time. Let the fall of the Columbia River, from this lake-shore east of the Cascade Mountains to the mouth of the Wallamet River, be stated at eighty feet. Our fossil remains on this lake-shore are two hundred and fifty feet above the present level of its waters, making a total of three hundred and thirty feet as the depth of those waters above the present surface at the mouth of the Wallamet River. How naturally one looks to the currents of such a vast body of water as the agency competent to the heaping up of that long, sandy ridge, one hundred feet high, through which the river has cut its way at Swan Island, north of Portland. But let us follow it still farther inland. Over where Portland now stands, these waters were three hundred and twenty-five feet deep; over Salem, one hundred and sixty-five feet; over Albany, one hundred and fifteen feet; over Tualatin Plains, one hundred and forty-five feet;
