Geology & Landscape | Fresh Water | Soils | Plants | Animals Scenic Quality | Cultural Landscapes | Sites of Interest Topics & Habitats

Geology and Landscape Development
Minas Basin and Cobequid Bay were carved out by rivers which eroded eastwards from the Bay of Fundy, cutting a channel along the Minas Passage Fault between Cape Split and Cape Sharp. The shape and profile of the entire Bay of Fundy was greatly affected by repeated glaciations during the Pleistocene. The floor is smooth and striated like a glacial pavement and covered by a mantle of loose material up to 10 m thick, some of which is glacial till. At the entrance to Cobequid Bay is a glacially scoured trough.

Around Cobequid Bay the Triassic red beds are nearly horizontal and form a low area with gentle undulations (see Figure 23). On the north side of Cobequid Bay, they attain their greatest width but then end abruptly at the Portapique Mountain Fault. The Triassic block has dropped down on the south side of this fault and now lies against older Carboniferous strata. West and east of Truro, Triassic deposits lie unconformably against Carboniferous Horton strata. In both areas the Carboniferous strata are harder and form low rolling hills. The boundary with the flat red beds is generally very distinct.

Salt marsh at low tide Click to enlarge

The Shubenacadie and Salmon rivers, which flow into Cobequid Bay, have drowned estuaries and buried river channels beneath the riverbed deposits. In the Truro area the incised channels of North River and Salmon River can be traced for 6 km and 8 km, respectively. They merge under the town and continue out to the Cobequid Bay, deepening to 40 m and narrowing to one kilometre, following the same course as the present river. These channels, cut in the sandstone bedrock, are filled with fluvioglacial outwash sands and gravels from the end of the last glacial period, about 10,000 years ago.

Much of the Triassic Lowlands from Truro to the north side of Cobequid Bay are covered by glacial deposits. The Truro sub-basin is filled with outwash sands and gravels carried from the north and east that form a plain elevated to 18 m above sea level; this plain is now dissected by streams. On the north side of Cobequid Bay, outwash deposits can be seen in the terraces of rivers. At Glenholme the underlying Triassic sandstone is exposed where the gravels have been washed away.

As sea levels continue to rise, the soft coastal red beds are being eroded rapidly, adding enormous volumes of sediment to the waters of the bay. This sediment is washed up and down the rivers with the tide, and some is deposited in the estuaries as sand bars; for example, in the Avon and Shubenacadie river estuaries.

As the coastline retreats, coastal marshes are also being eroded. In some cases the remains of fossil forests of beech, pine, Black Spruce, and larch are exposed.

Saltmarsh hay Click to enlarge

These trees were buried by bluish marine clay when the combined effects of rising sea levels and increasing tidal ranges brought salt water further up low-lying river valleys and over coastal lowlands. Once exposed to tidal action, the fossil stumps are quickly destroyed; however, new ones are continuously being exhumed. The rapid coastal erosion has created a wave-cut platform 100-300 m wide that borders the shore. This platform is commonly backed by low cliffs.

Fresh Water
The drainage pattern across the Triassic Lowlands in the Cobequid Bay area is broadly dendritic, with the rivers reaching the bay through drowned estuaries. The District is dissected by four secondary drainage divides. Along the north shore the streams flow steeply down off the Cobequids (Unit 311), forming numerous parallel tertiary watersheds, and are second- or third-order streams by the time they reach the lower elevation of District 620. Short, isolated first-order streams flow directly into Cobequid Bay along the south shore. Major rivers (such as the Shubenacadie, Salmon, Chiganois, and North) and several smaller streams influence seawater chemistry in the estuary at the head of Cobequid Bay.

There are many tidal marshes in the estuary and scattered along the coastline, concentrated in inlets and the mouths of rivers.

Soils
Hantsport clay loams occur along the narrow strip on the south shore of the Minas Basin. On the western side they are well drained but have imperfectly to poorly drained associates to the east. Around the town of Truro, well-drained Truro soils have developed from the red sandstone, with poorly drained associates covering approximately one-third of the area. Gravelly sandy loams of the Harmony series have also formed in this area over gravelly, sandy clay loams. Coarse Hebert soils on outwash sands, and finer-textured Cumberland and Stewiacke soils on alluvial materials, are found along streams and rivers. Large areas of Acadia soils have formed on dykelands at the head of Cobequid Bay.

Plants
This Unit is extensively farmed but differs from District 610 mainly in the presence of heavier soils.

Field of mustard, near Great Village Click to enlarge

Pine is therefore not as dominant a feature of the vegetation. Scattered Sugar Maple, American Beech, and Yellow Birch occur locally on low ridges, but spruce, fir, White Birch, Red Maple, Eastern Hemlock, and White Pine form relatively stable forests on other sites. Red Maple and Wire Birch replace Red Oak as post-fire species. White Spruce, Red Spruce, and Balsam Fir are the usual invaders of oldfields. Heathlands with Jack Pine are found in the Debert area, and the Minas Basin is fringed with areas of salt marsh. Rich intervale sites in the Truro area support Alleghanian floral species.

Animals
This District provides a mix of forested and open land and intertidal habitats occupied by a fauna similar to that described in District 610. The south coast of Minas Basin and Cobequid Bay is regionally important because of the significant concentrations of shorebirds in late summer and early fall, and the moderate numbers of waterfowl. The north shore of Cobequid Bay is also visited by several thousand shorebirds in August and September, and by waterfowl in spring and fall - mostly Black Duck with some Canada Geese. The provincial waterfowl sanctuary near Debert has a unique population of American Wigeon and several hundred geese use this wetland in the fall. A small population of Gray Partridge occurs in open dykeland and coastal farmland. Freshwater fishes include Creek Chub and Brook Trout. Anadromous species, such as Atlantic Salmon, Atlantic Sturgeon, American Shad, Striped Bass, and Rainbow Smelt, occur in Cobequid Bay. In order to spawn, many thousands of shad enter the Shubenacadie River, and Atlantic Salmon enter most Cobequid Bay rivers.

Scenic Quality
This area shares many of the Valley's scenic characteristics: it is a narrow and elongated farming region based originally on dyking of tidal marshlands. The water element, however, is more visually prominent (as the District forms a narrow fringe around Cobequid Bay) and relief is more muted. With the exception of the stretch west of Economy, there is no dramatic escarpment to mark the northern edge of the District; rather the land rises gently to the slightly more elevated Carboniferous Lowlands. From the southern side of Cobequid Bay, however, the Cobequid Hills provide a distant backdrop to a northward view.

Cultural Landscapes
An excavation at Debert uncovered an important Paleo-Indian campsite estimated to be 11,000 years old. Artifacts indicated that these early peoples hunted Woodland Caribou that had migrated northward after the retreat of the glaciers. In the seventeenth century, Acadians first settled in tidal-bay marshland areas that could be dyked to create fertile farmlands. After their 1755 deportation, Planters, Loyalists, and others settled much of this land, with an important farming

Marsh and mud flat Click to enlarge

area established around Truro. Today, farmlands here support the highest concentration of dairy cows in Nova Scotia. Timber supplied a thriving shipbuilding industry in the late 1800s, aspects of which are documented at Maitland's Lawrence House Museum, the home of shipbuilder and designer W.D. Lawrence. Hardwoods from the Cobequid Hills supply lumber to the Bass River Furniture Company. A large barite deposit near Walton was mined for 30 years, closing in 1971. Walton was also the site of an early tidal mill, where water power was used to grind grain or saw lumber. In the 1970s the tidal bay was seen as a candidate site for a large tidal power project. Peat is now exploited in the tidal bay area for the horticulture market.

Sites of Special Interest

• Walton (Whale Cove) - Triassic sandstones (Wolfville Formation) unconformably overlie the vertical Horton red siltstones exposed at low tide
• Route 215 between Maitland and Cambridge - road follows the boundary between the low Triassic coastal fringe and the adjacent rolling Carboniferous hills
• Inner Minas Basin shoreline - coastal sections of Triassic sandstone with plant fossils and bones of early dinosaurs
• Salter Head, Maitland - low sandstone cliffs fronted by a wave-cut platform and large sand bars in the estuary of the Shubenacadie River
• Selma - large sand bar
• Victoria Park, Truro - a river gorge carved during Triassic times in the Carboniferous Horton Group and now being exhumed by Lepper Brook; under the bridge in the park is an angular unconformity between the Horton Group and the younger Wolfville Formation
• Glenholme - glacial gravel overlying Triassic sandstone in the river terrace
• Debert Wildlife Management Area

Provincial Parks and Park Reserves

• McElmons Pond
• Anthony

Scenic Viewpoints

• Highway 215, east of Selma (view over Cobequid Bay)
• Burntcoat loop
• Highway 2, Economy to Lower Economy

Associated Topics T2.6 The Triassic Basalts and Continental Rifting T3.3 Glaciation, Deglaciation and Sea-level Changes T6.4 Estuaries T7.1 Modifying Forces T11.5 Freshwater Wetland Birds and Waterfowl T11.6 Shorebirds T11.13 Freshwater Fishes

Associated Habitats H2.4 Mud Flat H2.5 Tidal Marsh H6.1 Hardwood Forest (Sugar Maple, Yellow Birch, Beech Association) H6.3 Mixedwood Forest (Spruce, Fir, Pine-Maple, Birch Association) Associated Offshore Unit 913a Minas Basin