The Northumberland Plain is divided into two sub-Units:
(a) Northumberland Strait
(b) St. Georges Bay

Geology and Landscape Development

Northumberland Strait (sub-Unit 521a)
This coastal plain stretches from the Cumberland Basin

Salt marsh, Northumberland Strait Click to enlarge

to Pictou and Merigomish Island and is underlain by fine red sandstones of the Late Carboniferous Pictou Group (from Merigomish to Knoydart, Canso strata predominate). These sandstones have been thrown into broad folds. In Cumberland County there are two main anticlines: one runs from Pugwash Harbour west to Nappan, Amherst Point, and the area south of Minudie; the other runs from Malagash Point past Oxford and then plunges downward east of Springhill. The crests of these anticlines have been partially eroded away, exposing underlying Windsor evaporites or Canso Group strata. Gypsum outcrops in many places.

In addition to the two main anticlines, there are many minor folds which run east-west before plunging downwards. Differential erosion has created ridges and valleys parallel to the fold axes, creating an undulating landscape. In central Cumberland County, they rise to 120 m or more, for example, Streets Ridge east of Oxford.

Alternating low ridges and valleys determine the outline of

Near Merigomish Click to enlarge

the coast along Northumberland Strait (see Figure 17). The ridges run out to sea as headlands at Pugwash and Wallace, and nearly enclose Tatamagouche Bay and Amet Sound. Smith Point, Malagash Point, and Cape John are prominent projections; Caribou Island is a continuation eastwards of the Pictou County shore; and Pictou Island is a remnant of a ridge that existed in the centre of the Northumberland Strait.

Valleys form inlets and harbours along the coast where estuaries of the river were drowned by a rise in sea level.

At the eastern end of the Cobequid Hills the strata have been domed up as the once-underlying crustal block of the Cobequids rose upwards. Consequently, due west from Pictou, progressively older rocks are exposed - Early Carboniferous to Late Devonian to Middle Devonian. These strata become progressively more resistant and form a hilly upland projection at the eastern end of the Cobequids in District 320 (see Figure 9).

From Merigomish to Knoydart, the Northumberland Plain continues as a submerged rolling coastal lowland.

St. Georges Bay (sub-Unit 521b)
Middle Carboniferous strata (Windsor, Canso, and Riversdale) underlie a lowland on the south side of St. Georges Bay.

Pomquet Beach Click to enlarge

Elevations rarely exceed 50 m. Fine red Canso and grey-brown Riversdale sandstones and siltstones predominate, with a faulted block of Windsor evaporites exposed east of Antigonish. This band of Windsor strata has been eroded and drowned to form Antigonish Harbour. In places where gypsum outcrops, karst topography has developed. At Crystal Cliffs to the north, a 75-m high cliff with bands of white and pink gypsum faces the bay.

On the south side of St. Georges Bay,drowned river valleys that cut through Carboniferous rocks have created several harbours: Pomquet, Tracadie, Little Tracadie, and Havre Boucher.

A variable but ubiquitous cover of glacial till is found throughout the area. Eskers and outwash material are found along River John and elsewhere where rivers carried meltwater from the ice cap over the Cobequids.

Freshwater Environments and Coastal Wetlands
The streams flowing over the lowlands east of Amherst lie in an area of gentle topography and branch irregularly to form dendritic drainage patterns. Most of sub-Unit 521a lies north of the primary watershed boundary that dissects the Cobequids (Unit 311). Five secondary and numerous tertiary watersheds drain north in this part of the Unit. Streams flowing northwards from the Cobequids have been superimposed on bands of alternating weak and resistant strata. The Wallace River, for example, flows directly north from Folly Lake into the Northumberland Strait; its tributaries are adjusted to bands of weaker rocks and join it at right angles to form a trellised drainage pattern. River Philip and River Hebert also have tributaries that have adjusted to the strike of the strata. A small area in the southwest that includes the Nappan River drains west into Cumberland Basin. Flat bogs and swamps are widely scattered in the northwestern areas, and beaver-influenced wetlands are common throughout. Inactive beaver flowages become wet meadows and shrub swamps. Wide floodplains occur along some of the slow-moving mature rivers, such as the Pictou, West, Middle, and Merigomish rivers (see Figure 19).

Lakes on this coastal plain are infrequent, and those that occur tend to be elongated and shallow. Stratified lakes, such as Layton Lake in sub-Unit 521a, are meromictic. Surface-water pH levels are generally alkaline, ranging from 6.5 to 8.0.

The Northumberland Strait sub-Unit (521b) also drains north. It is bisected north-south by a secondary watershed boundary, and numerous tertiary and coastal watersheds drain into St. Georges Bay. A few small, scattered bogs are found in the western areas.

There are brackish lakes at Oxford and salt springs between River Philip and Springhill. The coast is characterized by extensive intertidal marshes and subtidal Eelgrass beds. Barachois ponds and tidal marshes occur in the harbours and inlets.

Soils
The sandstones and shales that underlie the entire area have produced glacial tills of a sandy loam to sandy clay loam texture. One common characteristic is the tight, impermeable nature of the subsoil. This effectively prevents rapid vertical movement of water, which must therefore be removed laterally, or through evapotranspiration. The most common soils are Debert, an imperfectly drained sandy loam, often with fragipan development; and Queens, a fine-textured, imperfectly drained sandy clay loam. Well-drained soils include Pugwash and Tormentine series on rolling topography. Kingsville and Masstown series occupy most of the poorly drained sites. Hebert soils on outwash materials, and Cumberland and finer-textured Chaswood soils on alluvial materials, are common along streams and rivers.

Plants
This Unit falls within the Maritime Lowlands Ecoregion of Loucks' Red Spruce, Hemlock, Pine Zone. The forests are heterogeneous mixtures of early to mid-successional stages dominated by hardwoods and much influenced by site characteristics and disturbances. Black Spruce, Jack Pine, White Spruce, Red Spruce, and Red Maple are the most abundant species, although Eastern Hemlock and White Pine are not uncommon. Eastern Hemlock may occur in pure stands and can be among the first species to colonize disturbed areas. Larch and Black Spruce occur in the extensive boggy areas. American Beech and Sugar Maple are found on a few slopes near the larger streams. Repeated fires have encouraged Jack Pine, especially around Oxford. Although large numbers of poplar remain in the area, they are gradually being replaced by conifers. Much of the area is farmed, and oldfields generally recolonize in alders followed by White Spruce. Larch more commonly colonizes wet fields underlain by fragipan along the coast.

Winds from the Northumberland Strait, often recorded at twice the speed of winds inland, are a strong influence. Trees often lean away from the wind, have one-sided crowns, and do not attain full height. Extensive salt marshes and Eelgrass beds occur in bays.

Animals
This Unit provides mostly oldfield, agricultural, and mixed forest habitats. The amount of abandoned farmland is significant. Relatively flat topography and imperfectly drained soils have resulted in an abundance of beaver-influenced wetlands. The coyote is common, especially in areas associated with agriculture. This is an excellent area for muskrat, mink, and raccoon and provides average habitat for Red Fox. River Otter occur but are not numerous. Freshwater habitats are relatively productive and support an enriched fauna, including Atlantic Salmon, Gaspereau, Brown Trout, and Brook Trout. The rare Brook Stickleback is found in this Unit, as is the threatened Wood Turtle, which can be seen along the abundant river habitat.

Many water birds breed mainly in coastal habitats, and many other

Can you spot the Herons in this Saltmarsh? Click to enlarge

species breed in freshwater marshes, which mostly arise near the coast. Given the steep rocky shores and extreme tidal range around the Fundy coast, most species in these bird groups breed in Cumberland County, where the extensive intertidal areas formed by the very shallow slope of the sea bottom provide appropriate waterfowl breeding and staging areas. This occurs mainly in sub-Unit 521a and Unit 523. These species include most ducks and marsh birds, Osprey, Bald Eagle, Semipalmated Plover, and Common Tern. Another group of birds, including Red-breasted Merganser, Willet, Herring Gull, Great Black-backed Gull, and Sharp-tailed Sparrow, breed in suitable situations on both low-lying and steeper coasts, appearing only in sub-Unit 521a and Unit 710.

The most significant bird habitats are around Fox Harbour, Wallace Harbour, Tatamagouche Bay, Brule Harbour, and John Bay, where large numbers of ducks and geese congregate in late March and April, and again in September until ice forms in December. Other important areas include Coldspring Head and the mouth of the Shinimicas River; Pugwash Harbour and River Philip; Caribou Harbour; Pictou Harbour, East River, Middle River, and West River; and Little Harbour and Merigomish Harbour. Freshwater impoundments are breeding areas for Pied-billed Grebe, American Bittern, Northern Harrier, Virginia Rail, Sora Rail, and many ducks.

Various bird species, such as Spruce Grouse, Northern Waterthrush, and Mourning Warbler, that are more characteristic of cooler areas are scarce in sub-Unit 521a. However, a few forest birds, such as Broad-winged Hawk and Brown Creeper, are widespread in this sub-Unit but scarce or absent in Units immediately to the south. Rough-legged Hawk, Snowy Owl, and Snow Bunting occur in winter on fields in the more upland areas of sub-Unit 521a.

The Northumberland Strait is a very distinct marine area in which warmer-water species such as oysters and quahogs are found.

Cultural Environment
Coastal areas of the Northumberland Plain had traditionally been the summer camps of the Mi'kmaq, and many place names in this area are derived from Mi'kmaq words. Antigonish meant "the place where branches are torn off the trees by bears gathering beechnuts" and Tatamagouche, situated at the mouth of the French and Waughs rivers, meant "the meeting of the waters." Settlers of largely English and Scottish descent cleared much of the land for agriculture, which continues to be an important economic activity. This area once supported many grist mills.

Farming, forestry, and fishing serve as the economic base for most

Warm water, red sand beach. Click to enlarge

communities here. Agricultural land in the Northumberland Plain is multi-cropped. The largest concentration of small fruit growers in the province has earned Cumberland County the title of "Blueberry-Growing Capital of the World." Vineyards at Malagash produce good quality grapes for wines. The marine life from the Northumberland Strait has been extremely important to the economies of coastal communities on the Northumberland Plain, with lobster, scallop, and oyster fishing predominating. Important seaweed beds of Irish Moss and Furcellaria are also harvested commercially.

This area features significant mineral deposits and mining operations. The earliest recorded exploration for copper in the province was near Caribou in 1828, and a small amount of copper production was achieved from mining chalcocite along the Wallace River. In 1946 a huge deposit of salt was discovered at Nappan and, since then, salt mines have operated both there and in Pugwash. Salt deposits at Malagash were mined for 40 years, and deposits up to 450 m thick have been drilled in this area. Today, limestone is mined at Southside Antigonish Harbour to supply the Scott Maritimes paper mill at Abercrombie, which processes pulpwood from surrounding areas. Red and grey sandstones at Amherst and Wallace were quarried to provide building stone for Province House and Government House in Halifax, as well as many other buildings of the early nineteenth century.

Various wildlife management areas (Wallace, Abercrombie) and the Brule Point Game Sanctuary are also found on the Northumberland Plain. Ducks Unlimited has converted many old, inactive beaver flowages back to shallow marshes. Cottages occur along stretches of the coastline. These are the warmest waters for swimming on the Nova Scotia coastline.

Sites of Special Interest

• Crystal Cliffs - 75-m cliff with bands of pink and white gypsum
• Antigonish Harbour - drowned estuary, karst topography
• Pugwash - salt mines
• River John - outwash deposits and eskers
• Oxford - round, water-filled sinkholes make small lakes
• Streets Ridge (120 m high) - brackish lakes
• Amherst Point - sinkholes
• Laytons Lake - a flooded gypsum sinkhole that is permanently stratified
• Pomquet Beach - best example of a prograding dune system in the province
• Amet Island - the only offshore islet with breeding seabirds (gulls and cormorants) in sub-Unit 521a
• Smith Point/Oak Island flats - the most significant area in sub-Unit 521a for shorebirds, with up to 12 species present in late summer, including concentrations of the rare Hudsonian Godwit
• Linden Bay - often significant for Canada Geese and currently the most regular stopover site for migrating Brant in spring
• Tidnish Dock - a useful vantage point for viewing water birds on the extensive shoal waters of Baie Verte and the most regular location in sub-Unit 521a for Red-necked Grebes in autumn
• National Wildlife Areas - Wallace Bay, Chignecto (includes Lusby Marsh and Amherst Point Bird Sanctuary)
• Provincial Wildlife Management Area - Antigonish Harbour, Federal Migratory Bird Sanctuary
• Black River Road (IPB Proposed Ecological Site 6) - Jack Pine forest
• Balmoral Grist Mill - example of early agricultural technology
• Sutherlands Steam Mill, Denmark - once manufactured carriages, sleighs, sleds, and doors from local timber
• McCulloch House Museum, Pictou - home of Thomas McCulloch, one of Nova Scotia's great naturalists and educators
• Northumberland Fisheries Museum, Pictou

Provincial Parks and Park Reserves

• Tidnish Dock (also an historic site of the Chignecto Ship Railway)
• Northport Beach
• Heather Beach
• Gulf Shore
• Fox Harbour
• Tatamagouche
• Barachois Harbour
• Balmoral Mills
• Shinimicas
• Rushton Beach
• Cape John Beach
• Waterside Beach
• Mackenzie Beach
• Doctors Island
• Caribou
• Lyons Brook
• Boat Harbour
• Powells Point
• Melmerby Beach
• Merigomish Harbour
• Big Island
• The Ponds
• Mahoneys Beach
• Pomquet
• Bayfield
• Barrios Beach
• Cape Jack Beach
• Malagash - Beatty Marsh Park Reserve

Proposed Parks and Protected Areas System includes Natural Landscape 22.

Scenic Viewpoint

• Unit 521a: Hardwood Hill, looking east over Pictou Harbour

Associated Topics T2.4 The Carboniferous Basin T3.2 Ancient Drainage Patterns T3.3 Glaciation, Deglaciation and Sea-level Changes T3.4 Terrestrial Glacial Deposits and Landscape Features T8.2 Freshwater Environments T9.3 Biological Environment T11.5 Freshwater Wetland Birds and Waterfowl T11.13 Freshwater Fishes T11.17 Marine Invertebrates T12.3 Geology and Resources T12.11 Animals and Resources

Associated Habitats H1.1 Offshore Open Water H1.2 Offshore Benthic H2 Coastal H3.1 Freshwater Open-Water Lotic H3.3 Freshwater Bottom Lotic H3.5 Freshwater Water's Edge Lotic H5.2 Oldfield H6.2 Softwood Forest (Pine Association; Black Spruce, Larch Association)