River Terraces of the Middle Humber River, Ontario

The terraces of the river valleys in southern Ontario provide one way of establishing at least part of the denudation chronology of the region. The paper reports the findings of an investigation centered on the Middle Humber Basin. (The Humber River is located west and north of the city of Toronto.) Two areas, within the basin, were studied extensively-the Kleinburg-Elder Mills area and the Woodbridge area. A threefold terrace sequence was established. When evidence for the causation of the terraces was collected, alternation in lake level was found to be the key factor. Three lake levels were found: 525 foot, 465-475 foot, and 420 foot. These elevations mark falling lake levels; the highest terraces the oldest, and the lowest the youngest