From its apparent relationship in either of these localities it might be taken to be a member of the Lower Huronian series just described, and equivalent to the basal conglomerate. In the Obushkong area it is probably underlain by Laurentian, for it lies nearly horizontally, and Laurentian is known to occur a short distance east of the lake. In the neighbourhood of Lake Timiskaming it is said to grade imperceptibly into granite, and is believed to be derived from the latter by detrition in situ. Arkose, apparently identical with that under consideration, occurs in the Cobalt district, and is thought to lie unconformably with the greywacke, and for this reason is classified as Middle Huronian. In these pages it is given no definite position in the formational succession, and as there is no field evidence of its Middle Huronian position, is not differentiated from the lower series. _Structural Features and Disturbances._ The Huronian has been subjected to no very severe disturbance, judging by its present condition and attitude. Frequently the strata lie almost horizontally, as for instance at the south end of Firth lake, and in the vicinity of Lake Lehmann, but over the most of the region they rest at inclinations as high as 30°, this attitude remaining constant over extensive areas, and developing a characteristic topographical feature. From Pigeon lake eastward the dip is uniformly to the east at angles ranging between 15 and 30 degrees and the beds overlap one another after the fashion of slates on a roof, the resultant topographical expression of which is a succession of north and south ridges with gentle eastern slopes, while the western sides form escarpments. This condition appears constant over all the Huronian east of a line midway between Pigeon and Duncan lakes. To the extreme north-west, however, a westerly dip was observed; the strata forming the 550 foot hill west of Duncan lake are also either horizontal or dip gently to the west. A confident statement cannot be made until further work has been performed, but the condition just outlined suggests a large anticlinal structure whose arch lies a little west of Duncan lake. However, there seems reason to believe that the structure is more complicated than would result from simple arching and erosion. If the present overlapping system represents the original succession of strata a total thickness of over two miles would be necessary, and there would be not two but several conglomerate horizons, which is improbable. A satisfactory solution is hindered by the general fact that planes of possible dislocation occur in low ground and are obscured by swamp or water, but it seems evident that tilting was accompanied by lateral or vertical displacements.