422 South Mountain Slope
| Geology | Fresh Water | Soils | Plants | Animals Cultural Environment | Sites of Interest | Topics & Habitats |
This Unit has two subdivisions:
(a) Bear River
(b) Gaspereau Valley
Geology and Landscape Development
The two sub-Units of the South Mountain Slope - Bear River and the Gaspereau Valley - are underlain by Halifax slate (Cambrian
-Ordovician) interfolded with White Rock Group volcanics (mostly ash) and sandstone (Silurian); and Torbrook sandstones and
siltstone (Early Devonian). The younger White Rock and Torbrook deposits are preserved in synclines.
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The slates, sandstones, siltstones, and ash deposits are truncated to the south by contact with the South Mountain Granite (see Figure 25). To the north they are overlain by soft Triassic deposits in the Annapolis Valley. They are therefore intermediate in hardness and form a dissected shoulder to the granite next to the low-lying valley floor. Deep valleys have been cut in these rocks, which are relatively unresistant, compared to the granite outcrops to the south. Bear River has cut a deep valley across the fold axis of the slates to reach the Annapolis Basin, which is cut into even less-resistant sandstones. The Gaspereau, in contrast, follows the fold axis and flows parallel to Annapolis Valley sandstones before emptying into the Minas Basin.
Bear River (sub-Unit 422a)
Bedrock in the Bear River area is overlain by a thick glacial till derived from the Halifax slate. This, in turn, is overlain by a thin,
clay till veneer. Along the coast are thick deposits of outwash gravel which form a series of terraces from The Joggins in the
west to Cornwallis in the east. These date from the immediate post-glacial period when the sea level rose rapidly as the ice caps
melted. The sands and gravels washed down from South Mountain formed terraces, beach deposits, and deltas at sea level. When
the land rebounded in response to the removal of the ice, the sea level became relatively lower and deposits were left well above
high tide. At the same time, in response to the lowering of the sea level, Bear River and Acadia Brook deepened their valleys.
Gaspereau Valley (sub-Unit 422b)
The western part of this sub-Unit is covered with Rawdon till, a ground moraine derived from a mixture of slate, sandstone, and
carbonate rocks. Along Halfway River, north and south of Greenfield, are pockets of glacially derived gravel that may be kames
and kame terraces. Eskers are also indicated.
An interesting geographic feature in this area is the classic example of river capture shown by the Gaspereau River. The Gaspereau, with a lower base level, has cut back towards the Black River, which originally flowed directly northwards through Deep Hollow to join the Cornwallis River. The Gaspereau eventually captured the headwaters of the Black River, leaving an undersized stream to flow through the original valley and a wind gap just north of White Rock.
Fresh Water
Rivers make up most of the surface water in this Unit. Bear River divides sub-Unit 422a and is tidal where it drains into the
Annapolis Basin. The pH level has been recorded as low as 4.7. Several large rivers and smaller streams flow down from the South
Mountain into the Annapolis Valley in sub-Unit 422b. Levels of pH in the larger rivers range between 5.1 and 5.9; Sunken Lake
has a pH of 7.4.
Soils
Soils derived from shaly loam glacial tills characterize this Unit. Bridgewater soils, derived from slaty till, and its associate
Riverport and Middlewood soils dominate the Bear River area (sub-Unit 422a). The proximity of various other rock types and
different directions of glacial movement has resulted in various other soils, including Wolfville (red-brown sandy till) and Digby
(outwash deposits). In the Gaspereau Valley (sub-Unit 422b), the reddish-brown shaly loams have produced Morristown soils.
Very steep slopes along the river valleys throughout the Unit have unstable soils with seepage spots.
Plants
The usually deep soils support productive mixed forest with spruce, pine, hemlock, aspen, and maple.
Animals
The Gaspereau Valley provides Bald Eagle wintering habitat. The Gaspereau River supports abundant fish spawning runs of Gaspereau, and Striped Bass are known to feed here.
In the cultivated lowland areas, small mammals are predominantly those species associated with non-forested habitats, for example, the Meadow Vole and Meadow Jumping Mouse. The small-mammal diversity is relatively high in well-drained, mixed, and deciduous forest habitats, especially along rivers and streams; elsewhere it is quite low. This Unit supports disjunct populations of the Southern Flying Squirrel.
Cultural Environment
This Unit has been extensively cut over and supports a considerable amount of agricultural activity. Planters, and later Loyalists,
settled in various parts of Bear River (sub-Unit 422a) and the Gaspereau Valley (sub-Unit 422b), which were soon cleared for
farmlands with relatively fertile soils. The stream now known as Bear River is derived from the name Hebert River, which appeared
on a map by Lescarbot published in 1609. Lumbering activities take place in wooded backland areas. Hydroelectric power has
been harnessed at Hells Gate. A hiking trail at White Rock in the Gaspereau Valley is a popular recreational spot.
- Bear River above highway bridge at Roop Point - gravel terrace 27 m above sea level
- Bear River, east of river mouth - gravels 30 m above sea level
- Deep Brook - terrace 42 m above sea level
- Smiths Cove - fine stratified sands 30 m above sea level
- The Joggins - fine sands extending westwards for 4 km
- Gaspereau Valley - river capture, and wind gap at Deep Hollow
Provincial Parks and Park Reserves
Proposed Parks and Protected Areas System includes Natural Landscapes 3 and 5.
Scenic Viewpoints
- Sub-Unit 422a: Bear River village
- Sub-Unit 422b: Nictaux Falls; South Mountain south of Morristown; Hells Gate trail at White Rock; Deep Hollow north of White Rock; South Mountain south of Gaspereau village
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