N.A. Ice Map
The Ice Age and Origins of the Humber Watershed
Toronto, Ontario


Overview of the
Humber River

Global and Continental Glaciation

Land Form Development in North America

Geological History
of the Great Lakes

Development of the
Oak Ridges Moraine

Geology of the
Humber River Watershed

Ecology & Recreation

Early Inhabitants

Maps of the
Humber River Watershed

Photo Gallery - Humber River Watershed
The Oak Ridges Terminal Moraine Map

A Map of The Oak Ridges Terminal Moraine

Part I - Introduction

A moraine is a glacially formed accumulation of unconsolidated glacial debris which can occur in currently glaciated and formerly glaciated regions, such as those areas acted upon by a past glacial maximum. This debris may have been plucked off a valley floor as a glacier advanced or it may have fallen off the valley walls as a result of frost wedging or landslide.

Moraines may be composed of debris ranging in size from silt-sized glacial flour to large boulders. The debris is typically sub-angular to rounded in shape.

Moraines may be on the glacier’s surface or deposited as piles or sheets of debris where the glacier has melted. Moraines may also occur when glacier- or iceberg-transported rocks fall into a body of water as the ice melts.

Terminal moraines, are ridges of debris deposited at the end of the glacier. They reflect the shape of the glacier's terminus. Glaciers act like a conveyor belt, carrying debris from the top of the glacier to the bottom where it deposits it in end moraines. End moraine size and shape is determined by whether the glacier is advancing, receding or at equilibrium. The longer the terminus of the glacier stays in one place the more debris will accumulate in the moraine.

There are two types of end moraines; terminal and recessional. Terminal moraines mark the maximum advance of the glacier. Recessional moraines are small ridges left as a glacier pauses during its retreat.

The Oak Ridges Moraine is the best example of a Terminal Moraine in S. Ontario with huge benefits to the inhabitants..

Click for Part II => Genesis of the Oak Ridges Moraine
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