423 Slate Ridges
| Geology | Fresh Water | Soils | Plants | Animals Cultural Environment | Topics & Habitats |
This Unit has two subdivisions:
(a) Rawdon Hills
(b) Wittenburg Ridge
Geology and Landscape Development
The Rawdon Hills and Wittenburg Ridge are two ridges of slate located at the margins of the Windsor Lowlands (Unit 511). They may both be ancient landscape features dating back to the pre-Carboniferous period. The Wittenburg Ridge may have been an island or peninsula in the Early Carboniferous sea that covered this part of the province,
because the Horton deposits wedge out on its flanks. The same does not appear to be true for the Rawdon Hills,
which were probably engulfed early in this depositional period.
The two ridges are abutted by Early Carboniferous deposits. Both Horton and Windsor deposits outcrop against the Rawdon Hills; the Wittenburg Ridge is almost surrounded by Windsor Group deposits. Where Halifax slate and Windsor deposits are juxtaposed, the latter are preferentially eroded, leaving the slate as higher land. This situation is in contrast to the more common relationship of slate and greywacke in which the slate, being softer, forms valleys (see Figure 11).
Both the Rawdon Hills and Wittenburg Ridge are covered by sheets of the reddish Lawrencetown Till, which is derived from the Carboniferous Lowlands, interspersed with locally derived grey till.
Fresh Water
Both ridges are drainage divides, but the Rawdon Hills are also crosscut by a number of streams that are tributaries
of the Avon River. The Herbert River, Meander River, and Glen Brook all have valleys which lie directly across the
ridge and which must have been superimposed by downcutting from a higher level. These three river valleys also
contain extensive deposits of outwash gravel on the northern side of the ridge where the slope meets the Windsor
Lowlands. The Wittenburg Ridge is the partial headwater for the Musqodoboit River system.
Soils
Rawdon Hills (sub-Unit 423a)
Soils in this sub-Unit have developed from slates and shales. Soils of the Rawdon catena are most common; they are shaly, sandy loams derived from slates and shales, ranging from rapidly to moderately slowly drained. Elmsdale soils also occur, derived from shales and sandstones, with slate and quartzite cobbles.
Wittenburg Ridge (sub-Unit 423b)
Queens clay loams occur on the slopes, with some imperfectly drained Hantsport soil north of Upper Musquodoboit. On top of the ridge, well-drained Kirkhill shaly loams occur, with small areas of poorly drained Middlewood and Riverport soils, developed from shaly loams.
Plants
Although the Rawdon Hills and Wittenburg Ridge are considerably lower than the other areas included in Loucks' Sugar Maple, Yellow Birch-Fir Zone (Maritime Uplands Ecoregion), they are still high enough to produce local climates that encourage shade-tolerant hardwoods. These occur as stands of Sugar Maple, Yellow Birch, and American Beech, but extensive cutting has produced a predominantly mixed forest with Red Spruce, Eastern Hemlock, pine, Balsam Fir, maple, birch, and ash. A vigorous understory of Balsam Fir and Red Spruce under hardwood stands is present throughout the Slate Ridges Unit. Pine is somewhat less common on the Rawdon Hills.
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
Both the Rawdon Hills and Wittenburg Ridge have hosted lumbering activity. Farming is marginal in these areas. Gold was once mined at settlements such as Gore. Stibnite, the chief ore of antimony, was mined intermittently at West Gore between 1884 and 1917.
- Sub-Unit 423a - Highway 14, east of Centre Rawdon
Provincial Parks and Park Reserves
Proposed Parks and Protected Areas System includes Natural Landscapes 29a and 29b.
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