Geology and Landscape Development
South of the Cobequid-Chedabucto Fault is a band of Horton rocks lying in a graben (a downfaulted block lying between two parallel faults). Across central Nova Scotia it is about 15 km wide and has an escarpment on the south that becomes increasingly prominent from the Eden Lake-Caledonia line eastwards.

Within the graben the elevations decrease gradually to the south and west.

Economy River, Colchester County Click to enlarge

In Pictou County the elevation is 225-240 m, falling to 175 m at the Southern Uplands and 120 m near Melrose. From Trafalgar westwards the drainage is all towards the St. Marys River confluence at Melrose (see Figure 18). The East River St. Marys drains along the Chedabucto Fault in southern Pictou County, eroding crushed material from the fault zone before heading southwards to Melrose. West River St. Marys has extended its headwaters along the line of the St. Marys Fault and has captured all the drainage flowing south across the graben in that area. Erosion by the river has exposed the fault scarp, which becomes increasingly prominent towards Melrose. The drainage pattern in the watershed of West River St. Marys and its tributaries is rectangular. The north-south and east-west directions probably reflect the joint pattern in the coarse Horton sandstones.

The western half of the St. Marys Fault Block is a uniform upland which runs along the southern side of the Cobequid Hills between the Cobequid Fault and the Portapique Fault. The Cobequid Fault forms the dividing line between the Avalon basement rocks of the Cobequid fault block to the north and the Carboniferous strata (Pictou and Riversdale) to the south. The Portapique Fault sets the Carboniferous rocks against the Triassic deposits which surround Cobequid Bay (see Figure 23).

Fresh Water
Unit 572 falls within three main watersheds. The headwaters of the East, West, and Middle rivers occur in the middle northern portions and drain into the Northumberland Strait. Along the southern margin of the Cobequids the relief becomes hilly as the fault blocks become narrow and are crosscut by fast-flowing streams draining into Cobequid Bay. The headwaters of the Calvary River occur in the western portion where the North, Salmon, Folly, Debert, and Chiganois rivers flow down from the Cobequids into the head and north side of Cobequid Bay (Unit 913a). The southern middle portion is part of the large watershed that drains the Stewiacke River into Cobequid Bay, and the headwaters of the Stewiacke are located in this part of Unit 572. Drainage is typically trellised with many first-, second-, and third-order streams. Freshwater productivity and diversity are high, and pH is generally between 6.0 and 7.5. Conductivity is low.

Soils
The tills derived from the hard grey sandstones of the Horton Group are midway between those derived from Halifax quartzites and those from the softer Shulie sandstones. Consequently, soils usually associated with both these bedrocks are found in this Unit. Halifax soils (well-drained sandy loams) occur with small areas of Aspotogan soil and peat. Shulie soils (gravelly silt loams to sandy loams) are more prevalent, with Springhill sandy loams and Millbrook gravelly clay loams. The western extension of this Unit south of the Cobequids has a complex mix of soils of all textures from gravels to clays.

Plants
The relatively flat, poorly drained topography and the extensive cutting in this

Bloodwort from Glencoe Intervale Click to enlarge

Unit have favoured conifers such as Balsam Fir, White Spruce, White Pine, Red Spruce, and Eastern Hemlock. Scattered Red Oak is found throughout. Mixed hardwood stands occur on some better-drained sites. The more gently undulating areas with shallow soils are dominated by spruce and fir. Extensive barren lands, apparently originating from repeated burning, are dominated by Sheep Laurel and Bracken with scattered pine, maple, and Black Spruce. A recent extensive burn near Trafalgar is now being replanted. C.D. Howe made the following observations on soil-forest relationships in 1912: "South of the railway to the height-of-land ... the country is made up of low rounded ridges and depressions. The higher points are covered with hardwoods, while the bases of the slopes and the forested depressions support mixed stands in which the conifers are in the majority. As a whole, one-half of the forested areas is composed of red spruce, fir and hemlock."

Two small floodplains in this Unit, one at Kemptown (Salmon River) and one at Glencoe (East River of Pictou), are of particular botanical interest because they support a rich and rare intervale flora.

Cultural Environment
Forestry is the main land use for much of this area. On bottomland river intervales, small farms are established, with pastureland sometimes climbing the base of surrounding hills. Former mining activity included the extraction of manganese in small quantities from Manganese Mines near Truro. Between 1849 and 1906, iron ore was mined almost continuously at Londonderry.

Sites of Special Interest

• Kemptown intervale (IBP Proposed Ecological Site 9) - Carolinian flora such as Wild Leek, Canada Lily and Blue Cohosh
• Glencoe intervale (IBP Proposed Ecological Site 10) - Carolinian flora such as Bloodroot and Horse-gentian
• Economy River (IBP Proposed Ecological Site 8) - old Red Spruce forest

Ecological Reserves

• Indian Man Lake

Provincial Parks and Park Reserves

• Two Mile Lake
• Guysborough Railway (part)

Proposed Parks and Protected Areas System includes Natural Landscapes 24, 26, 40, and 41.

Scenic Viewpoints

• Eden Lake (Highway 347)

Associated Topics T2.4 The Carboniferous Basin T8.1 Freshwater Hydrology

Associated Habitats H3 Fresh Water H5.1 Barren H6.1 Hardwood Forest (Sugar Maple, Elm Association)