Soils of Canada's Niagara Peninsula appellation

I covered the bedrock of Canada's Niagara Peninsula in my most recent post and will now turn to its soils.

In areas that have not been subjected to glaciation, there is a direct correlation between soils and the underlying bedrock as the former is the result of the weathering and decomposition of the latter. That direct relationship between soils and bedrock does not exist in glaciated regions (William R. Farrand, The Glacial Lakes around Michigan, Geological Survey Division, Michigan Department of Environmental Quality, Bulletin 4, Revised 1988 ):

• Soil material in any given area has been carried in from up to hundreds of miles away
• Ancient bedrock is generally covered with great thickness of drift material
• Soil is relatively young and the occurrence scrambled
• Drainage patterns are haphazard and immature

The Niagara Peninsula was covered by a 2 - 3-km thick sheet of ice -- the Wisconsin Glacier -- in a number of incursions from the north:

• Early Wisconsin > 65,000 years ago > 15,000 years duration
• Mid Wisconsin > 40,000 years ago > 8,000 years duration
• Late Wisconsin > 20,000 years ago > 8,000 years duration

These glacial incursions had two very important impacts on the Peninsula:

1. There is no record of sediments laid down during the Mesozoic and Cenozoic Eras as they were eroded and transported away by the advancing glacier
2. As the glacier retreated, water from the melting ice formed the precursors to today's Great Lakes
1. Glacial Lake Algonquin > Lake Superior, Lake Michigan, Lake Huron
2. Glacial Lake Warren > Lake Erie
3. Glacial Lake Iroquois > Lake Ontario
4. Glacial Lake Tonowanda > deceased

Lake Iroquois was an enlargement of the current Lake Ontario, the result of the ice sheet blocking the St. Lawrence River in the vicinity of today's Thousand Islands. This glacial lake was fed by Glacial Lakes Warren and Algonquin and drained to the southeast. The melting of the ice dam 12,500 years ago resulted in the lake dropping 85 m below its current level. Isostatic rebound of the tectonic plates (freed of the crushing weight of the glaciers) brought the lake up to its current level 4000 years ago.

The Niagara Peninsula is a typical glaciated environment.

Glacial Word/Term	Meaning
Till	A mixture of rock materials of all sizes from boulders to clay
End Moraines	System of hills traceable for many miles across the countryside
Ground Moraines	A gently sloping, hummocky deposit of till
Outwash Plain	Sheet runoff of meltwater flowing out and away from the ice front at the moraine Very coarse sediments near the moraine grade perceptibly to finer sands and silt further out The finest sediments are carried furthest away because they stay in suspension longest Clays settle out only upon reaching relatively quiet ponded water, such as in a lake

Source: Derived from Farrand.

The B part of the figure below shows the effects of glaciation. All of the terms and impressions mentioned in the table above are evident in the topography and the accompanying textual material. In addition, only the hard limestones and dolostones of ancient strata were able to weather the onslaught of the glaciers.

If we follow the path of the retreating glacier from south to north, we encounter the moraine structures of Fonthill Kame and Vinemount and the Haldimand Clay Plain seem to be text book example of an outwash plain where the heavier particles are closer to the moraine while the clays have been carried out to the Glacial Lake Warren and settled in great quantity. It should be noted that heavy clay soils can be problematic in grape-growing due to a lack of lime, phosphorous, and organic matter in the soil and poor drainage capability.

The Lake Iroquois Bench lies below the Niagara Escarpment and is divided up into four official sub-appellations. According to VQA Ontario, "The topography ranges from a distinct bench in the west Beamsville Bench, backed by steep cliff faces, through a double bench in the Twenty Mile Bench, to undulating hills in the East Short Hills Bench."

As it relates to Beamsville Bench (the sub-appellation within which Hidden Bench Winery Estate resides), the soils "... form a heterogeneous mixture of boulders, gravel, sand, silt, and clay, as well as bits of shale, sandstone and limestone from the continuing erosion of the Niagara Escarpment."

I will cover the region's climate in my next post

©Wine -- Mise en abyme