The Province of Quebec
Quebec is the largest province in Canada, and is surpassed' only by Ontario in population and economic development. Its shores were discovered more than four centuries ago and have been settled for nearly 350 years. The St. Lawrence is still the main gateway to a large section of North America.
Quebec extends from the international boundary at the 45th parallel of north latitude, to Cape Chidley on Hudson Strait at about 62° N., a distance of almost 1,200 miles. It thus spans several climatic and vegetation zones, from the deciduous forest to the Arctic tundra. Its greatest eastwest distance is over 1,600 miles, from the 57th meridian, at the Strait of Belle Isle, to the Ontario boundary at 79°33' west longitude. Quebec thus has two time zones. The North Shore of the Gulf of St. Lawrence and the Gaspé Peninsula fall in the Atlantic Standard Time Zone, four hours later than Greenwich Mean time, while the rest of the province has Eastern Standard Time which is one hour later.
The area of the province is 594,860 square miles, 15.5% of the area of Canada. It is a land of great diversity, 71,000 square miles being occupied by fresh water lakes and 160,000 square miles by treeless tundra, waste land and unproductive forest. An area of approximately 70,000 square miles is occupied by agricultural settlement and somewhat less than 300,000 square miles by productive forest, half of which is still untouched.
Quebec has the advantage of a lengthy shoreline. The uninviting coast from Cape Chidley to the southern part of James Bay is 2,550 miles long. The north shore of the Gulf of St. Lawrence and the estuary have a shoreline of 1,160 miles from Blanc Sablon to Quebec while it is nearly the same distance along the south shore and around the Gaspé Peninsula to the New Brunswick border at the head of Bale de Chaleur. The seaway is prolonged inland by the navigable waters of the St. Lawrence River and its tributaries. The largest cities of Quebec are located on the waterway and settlement has extended from its shores.
The province of Quebec falls naturally into three distinct but very unequal physiographic regions: (a) the Canadian Shield, sometimes called the Laurentian Plateau; (b) the St. Lawrence Lowland; (c) the Appalachian Highlands.
The Canadian Shield or Laurentian Upland
By far the greater part of Quebec, more than 500,000 square miles, is underlain by the hard old Precambrian rocks of the Canadian Shield. Because its nature was first known and studied in the rugged plateau-like highlands north of the St. Lawrence River, the name Laurentian is often used for the whole region. The rocks are, largely, granites, diorites, quartzites, gneisses, schists, and slates. Except on rounded hill tops and in stream gorges, however, the surface material is mostly of glacial origin, or the sand, gravel and clay deposits of the post-glacial period. The skyline as seen from the air is "monotonously even". The main trend of relief is a plateau-like surface arising from the sea-level, on the shore of James and Hudson Bays, to 1,000 feet in Abitibi, 1,500 feet in the Laurentian mountains, and above 2,000 feet along the Labrador boundary. Scattered monadnocks rise a few hundred feet above the upland in the interior, but the most conspicuous summits are found toward the eastern edge of the Shield in the Laurentide National Park north of Quebec City (3,900 feet), and Mont-Tremblant Park west of Montreal (3,150 feet).
Numerous cycles of erosion have reduced the Laurentian Upland to its present level. The history of peneplanation dates back to Precambrian Times. On the western margin of the Shield, fragments of old peneplains are buried beneath the Paleozoic sediments. Then a marine invasion occurred over most of the Laurentian Upland, and several hundred feet of Paleozoic sediments were accumulated. As the land was uplifted at the close of the Paleozoic period, a new series of erosion cycles, lasting for some 500 million years, removed the overburden of sedimentary rocks. But before the last glaciation, the region was uplifted again, and the rivers were rejuvenated. The active streams deepened their valleys, and with their tributaries have excavated large basinlike areas. Those cycles of erosion that took place before Quaternary glaciation shaped the basic features of the present physiography of the land. The three main peneplains of Quebec, referred to later, were formed before the occurrence of ice sheets.
The Appalachian Highlands
The Appalachian Highlands, extending from Alabama to Newfoundland, include South-eastern Quebec. They reach their widest extent in the Eastern Townships and their greatest relief in Gaspé where the Shickshock Mountains have many summits above 3,500 feet.
The rocks here are different from those of the Laurentian Upland. They are mostly sediments of the Paleozoic Era, ranging from Cambrian to Carboniferous. The Cambrian rocks are mostly altered sediments: quartzites, argillites, schists and slates; the other formations contain limestones, sandstones and conglomerates as well as schists and slates. The strata have been folded, broken and crushed by mountain building. In the process igneous rocks were intruded. Bodies of serpentinized peridotite date from the earliest period; basalts, granites, diabases and syenites appeared later. The intrusive rocks are harder than the sediments and stand out now as the highest summits.
The Appalachians became ridges of high mountains during the latter part of the Paleozoic Era. Two chief periods of mountain-building are known: the Taconic revolution at the close of the Ordovician; and the Acadian during the Devonian; other disturbances occurred later. Then came cycles of erosion lasting for more than 200 million years, until glaciation happened here as in all other parts of the Province. So, it is no Surprise to find in the Appalachian Highlands a smooth relief of plateaus and deep valleys with only a few ridges.
The highest summits are seen in the Gaspé peninsula. Mount Jacques-Cartier, Quebec's highest peak, rises to 4,160 feet and is surrounded by twenty others ranging from 3,500 to 4,000 feet. Westward the serpentine mass of Mount Albert is 3,775 feet high, and southwestward the bold range of the Shickshocks stretches for 55 miles towards Matapedia valley. Its highest summits are: Logan (3,700') Bayfield (3.470'), and Mattawa (3,370'). There is a great contrast in relief between the northern and southern shores of the peninsula. The first one is bold; in some places shore cliffs rise 800 to 1,000 feet; the other is low and irregular; the 1,000 foot contour lies some 25 miles away from the Chaleur shoreline.
Between the Matapedia and Chaudiere Valleys, very few summits rise above the old peneplain of 1,200 feet. Valley floors afford easy passages from the St. Lawrence estuary to New Brunswick. In the Eastern Townships the relief becomes bolder. From west to east, three parallel ranges are to be found: the Sutton range, extending from the Green mountains of Vermont into Canada, the Stoke range, from west side of lake Memphremagog to lake St. François and the Megantic range, close to the New Hampshire and Maine border. Amongst the highest summits are: Sutton (3,200'), Orford (2,860'), Chapman (1,800'), Gosford (3,875') and Megantic (3,620'). Between the ridges, the deeply dissected plateaus seldom exceed 1,200 feet in altitude.
The Pleistocene glaciation is nearly as evident here as in the Laurentian plateau. Ice erosion has deepened the long lakes such as Memphremagog in the south; Temiscouata and Matapedia in the north. A mantle of glacial drift covers the underlying rocks. The rivers were ponded back of the glacial ridges forming high level lakes. The moraines have yielded better soils for agriculture than in the Laurentians, especially when buried by more recent clay and sand deposits.
The St. Lawrence Lowlands
The smallest physiographic region of Quebec is a triangular lowland bounded by the edge of the Canadian Shield to the northwest, the great Champlain fault, bordering the Appalachian Highlands to the east, and the Adirondack Mountains in New York State, to the south. The underlying rocks are sandstone, shale and limestone of the Ordovician, Silurian and Devonian periods. The strata are gently dipping, or lie in low, broad, dome-like folds, traversed by faults, some of which are of considerable throw; but compared with the highly folded measures of the Appalachians, they seemed relatively undisturbed. The present surface is low and flat, especially around Montreal (100 feet), but it rises in the neighbourhood of Quebec City to about 300 feet. This uniformity is broken by the Monteregian Hills extending in a line from Montreal to the Appalachian Highlands: Mount Royal (769'), St. Bruno (712'), Beloeil (1,437') Rougemont (1,250'), Yamaska (1,470') and Johnson (875'). They are extrusions of igneous rocks that forced their way up during the Devonian period, when orogenic movements were active.
There need be little wonder that the relief is so low. The unfolded sediments were easily removed by the numerous cycles of erosion, the base-level being furnished by the antecedent St. Lawrence River. The hard igneous rocks of the Monteregian Hills stand as monadnocks. But here also glaciation left its marks. The course of the St. Lawrence was altered. Upstream from Montreal, the river forms a series of impounded waters: Lakes St. Louis and St. Francis, and many rapids: Lachine, Cedar, etc., Downstream, the glacier excavated a deep trough on the site of lake St. Peter, now being filled by river deposits. In front of Quebec City, the St. Lawrence had to find a new course and its cliffs are still very steep. After the melting of the ice the whole area was invaded by the Champlain Sea, whose deep clay deposits form valuable agricultural soils.