421 Sissiboo Lowlands
| Geology | Fresh Water | Soils | Plants | Animals Cultural Environment | Topics & Habitats |
This Unit has three subdivisions:
(a) Sissiboo Lowlands
(b) Meteghan Lowland
(c) Lake George
Geology and Landscape Development
These areas are underlain by synclines containing Halifax slate with, in the Sissiboo and Lake George areas, thicknesses
of Silurian White Rock volcanics.
The three sub-Units lie within the Digby-Yarmouth area and share the same complex glacial history. (See also Unit 411.) Four separate glacial phases have been recognized from the last ice advance. In the first phase the ice came from the east and produced a grey till derived from local material. The second pulse was the major one from New Brunswick, which engulfed the entire province and deposited a red till (Red Head Till) in this area. The third pulse of glacial ice, presumably from an ice sheet in Nova Scotia, flowed parallel to the coastline and deposited the Saulnierville Till. Finally, a weak flow from an ice cap on the Southern Upland deposited the loose material of the Beaver River Till. The Beaver River Till is at the surface of the quartzite and slate tills from which the soils have formed over most of the area. Both this and the Saulnierville Till contain fragments of Meguma Group rocks and White Rock volcanics. The relationship between the four different till layers is best seen along coastal sections, although occasionally inland a lower till is just partly covered and revealed in the centre of younger till deposits, for example, from Cape St. Mary north to Lac de Gruau.
The three areas differ somewhat in the composition of the Beaver River Till exposed on the surface. In the Sissiboo Lowlands and Meteghan Lowland, slate tills and drumlins predominate, whereas at Lake George the till and drumlins are composed predominantly of quartzite.
A few isolated deposits of water-deposited debris are present within this Unit; the best examples can be found along the shore of the Tusket River (Unit 831). There are one or two isolated eskers; one is found on the west side of Gaspereau Lake in the Meteghan Lowland.
Overall, the Sissiboo Lowlands have a low relief and a stony drumlin terrain.
Fresh Water
Lakes are numerous and are elongated north-south, often forming chains. Scattered wetlands are typically raised bogs
associated with fens. Swamps are also typical of the Sissiboo Lowlands. Several large areas of shrub swamp and marsh
are found in sub-Units 421b and 421c.
Freshwater is generally dystrophic. Conductivity levels range between 32 and 59 micromhos/cm, and pH levels range between 5.4 and 6.7.
Soils
Sissiboo Lowlands (sub-Unit 421a)
Well-drained Bridgewater and imperfectly drained Riverport soils, both sandy loams derived from slate, occur in this sub-Unit.
Meteghan Lowland (sub-Unit 421b)
Near the coast, Riverport and Bridgewater soils occur on gentle to undulating terrain. Further inland, well-drained Mersey
and imperfectly drained Liverpool soils have developed from schists and quartzite, accompanied by poorly drained,
mottled Pitman soils and areas of peat.
Lake George (sub-Unit 421c)
Moderately well-drained Yarmouth soils derived from schist and quartzite occur, with mottled Deerfield soils in areas with
less relief. Liverpool and Pitman soils occur on very flat areas. To the north of this sub-Unit some well-drained Medway
soils have formed on sands and gravels.
Plants
This entire Unit exhibits excellent forest growth on schisty and slaty soils. The Sissiboo Lowlands sub-Unit (421a) has
considerably more hardwoods than the other sub-Units. The terrain is rolling and, on better-drained sites, American Beech
and Red Oak with Sugar Maple, Yellow Birch, and aspen grow interspersed with shade-intolerant hardwoods. On
moderately drained sites, a Red Spruce and Black Spruce mixture occurs. Ash is found with the spruces on Deerfield soils.
The shade-intolerant Red Maple and White Birch are also mixed with ash on the Pitman soils. The Meteghan Lowland (sub
-Unit 421b) is predominantly mixed with Red Spruce, Black Spruce, Red Maple and White Birch. The Lake George sub-Unit
(421c) has been very heavily disturbed. Pure stands of White Spruce have recolonized oldfields and pastures, and
American Beech, Yellow Birch, and shade-intolerant hardwoods are abundant.
Shorelines of lakes and streams may include coastal-plain plants, some of which are considered rare in Nova Scotia.
Animals
An inland breeding colony of Black-backed Gulls and Double-crested Cormorants occurs at Lake George. Freshwater
habitats have a relatively rich aquatic fauna with some coastal-plain species of molluscs and arthropods. Fish species
include Smallmouth Bass, Yellow Perch, Brown Bullhead and White Sucker. Creek Chub, Atlantic Salmon, Brown Trout,
American Eel, and Gaspereau are also found in sub-Unit 421c.
Cultural Environment
Acadians settled parts of this area after the deportation of 1755. Forests supplied lumber for the shipbuilding industry
in the nineteenth century along the shores of St. Marys Bay. Much of the fertile land in this Unit has been cleared for
agriculture and many areas are still actively farmed. White Spruce is recolonizing abandoned farmlands. Hydroelectric
power was harnessed at Sissiboo Falls. The rivers support sport fishing for Brook Trout, Smallmouth Bass and Atlantic
Salmon.
- Placid Lake in sub-Unit 421a (IBP Proposed Ecological Site 56) - dystrophic lake, flood plains, and old Eastern Hemlock stand
- Cape St. Mary to Lac de Gruau in sub-Unit 421b - older till exposed in centre of younger till
Provincial Parks and Park Reserves
- Ellenwood Lake (sub-Unit 421c)
- Corberrie (sub-Unit 421a)
Proposed Parks and Protected Areas System includes Natural Landscape 5.
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