Geology and Landscape Development
The Mulgrave Plateau lies within the Avalon Zone of Nova Scotia. The Avalon basement strata are overlain by resistant Middle and Late Devonian rocks, including coarse sandstones and conglomerates with basalts, other volcanic deposits, and a dyke. These strata were deposited at about the time of the Acadian Orogeny when the Avalon and Meguma zone rocks joined together, and it is reasonable to expect that they would reflect these crustal disturbances.

The elevation on the Mulgrave Plateau reaches over 200 m on the west side, falling to below 130 m near the Strait of Canso. At Cape Argos and Chedabucto Bay it is about 50 m. The scarp along the Chedabucto Fault separates these Devonian rocks from younger Horton strata and is an important physiographic feature.

Apart from this regional slope to the east, there is little variation in relief on the plateau (see Figure 17). The upland surface is uniformly covered in a stony till, and there are few features of interest. One rather beautiful area lies along the Roman Valley where the river has exploited a fault line, producing a steep-sided valley which cuts into the plateau. The river flows into a large drowned estuary to Milford Haven and Guysborough.

Fresh Water
A primary watershed division bisects this Unit horizontally in the northern portion. The east side is drained by several tertiary watersheds into Chedabucto Bay. The western area falls within a secondary watershed draining the Salmon River system. There are many small, irregularly shaped glacial lakes. Surface water pH levels range between 6.2 and 6.8.

Soils
Soils in this Unit are derived mainly from shales and tend to be heavy and comparatively shallow (see Figure 28). Millbrook clay loams occur north of Chedabucto Bay. Elsewhere the soils are mainly Riverport and Kirkhill shaly loams, with some blocks of Thom sandy loams, associated with upland areas.

Plants
This Unit includes a wide variety of forest associations. On the deeper soils west of Mulgrave, mixedwoods predominate, with Balsam Fir, Black Spruce, Eastern Hemlock, Sugar Maple, and American Beech. On the wetter sites, Black Spruce, Balsam Fir, and larch occur, with White Spruce, Yellow Birch, and aspen appearing on better-drained sites. On shallow soils, such as those around Lincolnville, fir, Black Spruce, and White Spruce grow with larch, shade-intolerant Red Maples, birches, and aspen.

West of Middle Melford, where the clay soils have been waterworked, the better drainage encourages a mixed forest. The changing nature of the forest can be gauged from the following observations on soil-forest relationships made by C.D. Howe in 1912: "The forestal nature of the [western] portion may be characterized very briefly: barrens and semi-barrens interspersed with bogs and low hardwood ridges. The forest on the broad belt of Lake Lochaber is of the mixed type with hardwoods, chiefly yellow birch, forming one-half of the stand, the rest being red spruce and fir in about equal proportions. The crests of the hills and ridges are pure hardwood, 90 percent of which is often yellow birch, the remaining being beech, hard maple [Sugar Maple] and paper birch. East of the Cross Lake region to the Guysborough river, practically pure hardwoods prevail. As one approaches the coast from the interior, fir and spruce form a large proportion of the forest." This "forest" is the coastal forest (Region 800).

Cultural Environment
This area is sparsely settled, and forestry is the dominant resource activity. Farming takes place in river valleys. Communities on the Mulgrave Plateau are largely of Scottish descent. Black Loyalists settled the town of Lincolnville.

Sites of Special Interest

• Goshen - view southwards across the St. Marys Fault Block to the escarpment of the St. Marys Fault
• Roman Valley - steep-sided, V-shaped valley leading to a wide estuary near Milford Haven

Provincial Parks and Park Reserves

• Lochaber
• Giants Lake
• Port Shoreham
• Wharf
• Guysborough Railway (part)

Proposed Parks and Protected Areas System includes Natural Landscape 46 and Candidate Protected Area 12 Ogden Round Lake.

Scenic Viewpoints

• Pirate Harbour, on the Strait of Canso
• Roman Valley to Milford Haven
• Roachvale (Salmon River)

Associated Topics T2.2 The Avalon and Meguma Zones T3.2 Ancient Drainage Patterns T3.4 Terrestrial Glacial Deposits and Landscape Features T8.1 Freshwater Hydrology

Associated Habitats H3 Fresh Water H6.1 Hardwood Forest (Sugar Maple, Yellow Birch, Beech Association) H6.2 Softwood Forest (Spruce, Hemlock, Pine Association; Black Spruce, Larch Association) H6.3 Mixedwood Forest (White Spruce, Fir-Maple, Birch Association)