Less conspicuous than these great masses are certain minor, but persistent features which are directly referable to geological conditions. Within Huronian areas there is a distinct tendency toward the development of a system of parallel ridges similar in structure and mode of origin to the hill at the north-east of Duncan lake. This feature is developed with special regularity in the southern part of the wedge between Duncan lake and the West branch, where a succession of north and south ridges alternate with strips of swampy ground. The western faces of the ridge are bare and cliff-like, while the eastern slopes are gentle, well soil-covered and forested.
The post-Huronian diabase is an equally potent topographical factor. Its surface is one of marked irregularity, but the peculiarly distinctive features occur at its contacts with the Huronian. These contacts appear to be zones of low erosive resistance, and are commonly coincident with ravines, walled on one side by diabase, on the other by Huronian. Small lakes may occur at intervals along them as, for example, between Firth lake and the West branch. This erosion feature is well shown by the configuration of Gowganda lake, where diabase bodies are unusually abundant; both of the long arms to the north-west lie in trough-like depressions marking the edges of the eastern diabase mass. The same tendency in an incipient condition is observable on the east side of the large peninsula where a series of three land-locked bays extend along the contact between the eastern diabase mass and the Huronian. Near the middle of Duncan lake, a diabase-Huronian contact which crosses the lake diagonally is marked by two deep bays, one extending to the north, the other southward. While this tendency is an evident one it is not to be understood as invariable; the large island in Duncan lake between the two above-mentioned bays is sufficient to indicate that contacts may lie in high ground, yet even here there are minor features indicating the contact zone to be structurally weak.
Another less explicable topographic peculiarity becomes apparent only upon scrutiny of the drainage system. A brief consideration of the map shows that both East and West branches follow peculiar zig-zag courses running north for a short distance, then turning abruptly east, this feature recurring repeatedly. In some instances the east-west portion of both branches lies in the same line. In the case of Zigzag lake and adjacent portions of the West branch this feature is repeated with an almost conventional regularity, which precludes attributing it to chance causes. Many of the smaller lakes—Foot lake, for instance—exhibit the same character on a small scale. This abnormality has been commented upon by investigators in the country to the east, the courses there, however, being N.E.-S.W. and N.W.-S.E. Regional faulting is suggested in explanation. The canyon-like east and west walls of Zigzag lake suggest such conditions, but a discussion of the matter must be deferred until further data can be collected.
DRAINAGE.
All the drainage water escapes by way of the Montreal river, whose two chief tributaries are the East and West branches, the latter being considerably the larger. The East branch is without feeders of important size, but the West branch receives a large creek, the Wapus, from the south, and a considerable volume of water enters through Duncan lake.
In common with most rivers traversing the pre-Cambrian region, this water system is marked by a volume of dormant water enormously greater than that being transported at any given moment. With few exceptions the many small tributary brooks rise in lakes or groups of lakes surprisingly large in size, compared with the volume of the out-flowing streams; Otto and Lehmann lakes are drained by a rather sluggish rivulet 8 feet wide and 6ʺ deep, although their combined area is about two square miles. The larger streams themselves are only successions of irregular lake expansions which empty from one to another by short, river-like portions containing rapids and falls. The descent is therefore accomplished by a succession of abrupt steps rather than an evenly graded slope. This juvenile condition is directly ascribable to the geological character of the country; soil deposits are insignificant in quantity, leaving exposed a resistant and uneven rock floor in which the streams are unable to carve channels for themselves. Failing to do so they select the readiest egress by filling up impervious rock basins and spilling over at the lowest points into lower ones. In consequence of the scantiness of soils and frequency of natural settling basins, the waters of the whole system are free from suspended matter, and hence lack of an effective graving instrument. Exceptions to this general character occur in the extensive sand plain to the north and west of Duncan lake, where the several small creeks that traverse it are of ordinary fluvial form and gradation, and the waters of which transport large quantities of sand to Duncan lake.
FLORA AND FAUNA.
Where not recently burned the country is fairly well forested, the density and character of growth being dependent upon soil and drainage. The best timber is in low ground and near watercourses where conditions for growth are most favourable and the probability of fire least. Recent fires have done much damage around Nest, Obushkong and Gowganda lakes. Probably the best timber lies near Duncan lake. Trees do not grow very large as a rule and are not especially good for making lumber, but provide an abundant supply of materials for pulpwood, railway ties, fuel and for mine use.
White pine is the most valuable species, but although individuals attain thicknesses of 20ʺ to 40ʺ they are too scarce to render this timber worth the search. Good red pine is more abundant. Jack pine is a very common tree, especially in sandy districts, e.g., north-west of Duncan lake; but is small and worthless. The common and most widely distributed species are spruce, balsam, cedar, poplar, white and yellow birch. Tamarack is not abundant. Clumps of small red maples were seen to the south-west of Pigeon lake.
The East and West branches are not well suited for carrying logs as there are extensive lake expansions without current on each and the rapids are shallow. Excellent water-power is obtainable at the 40 foot fall on the West branch above Fort Matachewan.