The following is a list of the islands of the archipelago, having an area greater than 500 square miles:—
| Area | ||
| square miles. | ||
| Group I.— | Southampton | 19,100 |
| Group II.— | Baffin | 211,000 |
| Bylot. | 5,100 | |
| Group III.— | Banks | 26,400 |
| Victoria | 74,400 | |
| Prince of Wales | 14,000 | |
| North Somerset | 9,000 | |
| King William | 6,200 | |
| Group IV.— | Ellesmere | 76,600 |
| North Devon | 21,900 | |
| Bathurst | 7,000 | |
| Cornwallis | 2,700 | |
| Eglinton | 700 | |
| Prince Patrick | 7,100 | |
| Melville | 16,200 | |
| Axel Heiberg | 13,200 | |
| Ellef Ringnes | 4,800 | |
| Amund Ringnes | 2,200 | |
| King Christian | 2,600 | |
| North Cornwall | 600 | |
| ———— | ||
| Total area | 520,800 |
The configuration and the physical features of the islands depend upon the character of the rocks that form them; in consequence, a brief description of the geology of these northern regions is here given.
Granites, gneisses and other crystalline rocks, very similar to those forming the Archæan system of more southern regions, occupy the eastern shores of the great islands fronting on Baffin bay and Davis strait, from Smith sound to Hudson strait. On Ellesmere island these rocks form a wide band down the east side from the neighbourhood of Cape Sabine to Jones sound, where the western boundary is upwards of fifty miles from the mouth of the sound. They occupy the eastern part of North Devon, reaching, on its south side, some seventy miles up Lancaster sound. The whole of Bylot island and that part of northern Baffin island to the eastward of Admiralty inlet is formed of these rocks. The great island of Baffin has upwards of three-quarters of its area underlain by Archæan granites and other crystalline rocks, while the eastern side of Southampton belongs to that formation which is also found at Salisbury, Nottingham and Charles islands of Group I.
To the westward of this wide rim of Archæan rocks is a great basin which has been filled with deposits of limestone, sandstone and other bedded rocks belonging to the Palæozoic or middle formations of the earth’s crust. These rocks extend upward from the Silurian to the Carboniferous.
The lower rocks, consisting largely of limestones, are the most widely distributed. They extend southward and westward far beyond the limits included in this report. The rocks newer than these Silurian limestones are not found south of Lancaster sound and Barrow strait, except on the northern part of Banks island at the extreme west of the archipelago. These rocks of Devonian and Carboniferous age occupy the Parry islands and the western and northern parts of Ellesmere, and in many places contain good deposits of coal.
A yet newer series of rocks belonging to the Mesozoic are found along the western edge of Ellesmere and on the Sverdrup islands. Isolated patches of later Tertiary age probably also occur along the northern and eastern coasts of Baffin island, and are of importance in that they are often associated with deposits of lignite coal. Small areas of this age have been found in the Parry islands and on the western part of Banks island.
On these northern islands the country underlain by the crystalline Archæan rocks is very similar in physical character to like areas of more southern regions. Where these rocks occur, the coast is usually greatly broken by irregularly shaped bays and headlands. The shores are often fringed with rocky islands, and the adjacent sea-bottom is liable to be very uneven. The land, as a rule, rises rapidly from the coast into an uneven plateau or tableland, whose general level is broken by ridges of rounded hills which seldom rise more than a few hundred feet above the general level. The elevation of the tableland varies from a few hundred feet to an extreme height of nearly five thousand feet.
In the northern parts the surface of this Archæan tableland is usually covered with a thick ice-cap, through which only the loftier hills protrude. The valleys leading down to the coast from the ice-cap are filled with large glaciers which project into the bays, where they discharge numerous icebergs. As the ice-cap becomes thinner in the more southern parts the glaciers become less active, and generally terminate without reaching the sea, and consequently no icebergs are formed from them.
The country, formed of the limestones and other Palæozoic rocks, differs in its physical character from that already described. On the northern islands, where these rocks attain a considerable thickness, the land rises in abrupt cliffs directly from the sea. The summits of these cliffs vary in elevation from 1,000 to 3,000 feet, while the country behind is a tableland rising in steps inland, the front of each step being a cliff usually of much less thickness than the initial one by which the land rises from the sea. In the more northern islands the higher portions of these tablelands support ice-caps generally much thinner than those covering the adjoining Archæan tablelands. The coasts composed of these flat-bedded limestones are deeply indented by narrow bays or fiords in the valleys of the more important streams; each small stream and rill flowing off the land has left its sculptured mark upon the cliffs, so that the whole resembles, on a great scale, the banks of a stream cut into a deep deposit of clay. This minute sculpturing of the rocks points to their having been elevated above the sea for a very long period, during which time the streams were actively at work cutting their valleys down to the sea-level.