For over half a century the certainty of some post-Glacial submergence of northeastern America has been recognized, yet the maximum submergence or, conversely, the height of the subsequent uplift and the limits of the affected area have not been determined. In recent years there has been a tendency to minimize the diastrophic movement and even to deny its occurrence along the south border of the glaciated territory; but Professor Shaler believed that Marthas Vineyard had been submerged 300 feet and Mount Desert 1,300 feet, and several eminent geologists have found abundant and positive proof of Pleistocene submergence of the lower Hudson Valley and New Jersey (see number 84 of the bibliographic list, page 288). The radical difference of opinion on a subject open to direct observation is a problem in psychology.
Canadian geologists have recorded many localities of marine fossils at high altitudes in the Saint Lawrence and Ottawa valleys . . .