Page:The Journal of geology (IA journalofgeology11893univers).pdf/368

ridge of Riga Schist is seen at A outlined from the surrounding Egremont Limestone by a dotted and dashed line. At B and C are seen Turnip Rock and Barack M'Teth, composed of Everett Schist. Between A and C the average strikes in the limestones are nearly east-west, and the dips (due entirely to pitch) about 30° south. Approaching Turnip Rock the strikes become northerly and the dips easterly, as the limestone mantles around the ridge A.

A second elevated area of the Riga Schist having three principal undulations in the direction of its prevailing strike,

Fig. 2.Diagrams illustrating some of the structural features of the area studied. A, Flexures in crest-line of the western ridge of Riga Schist. B, Flexures in Tom's Hill and region to the west (from section F, Plate VI). C, Diagram showing the corrugated character of some of the smaller schist knolls near Salisbury. D, The same in section. E, Diagram showing the probable manner of development of small steep thrusts in the sharply folded region southeast of Tom's Hill, and in Horse and Peck's Hills.

corresponding with the three undulations of the western schist anticlinal, is traced along the eastern margin of the district. The northern of its three undulations brings to the surface in Peck's Hill, schist areas 26 and 19, and the accessory overturned and ruptured fold of areas 22-24; while the central undulation brings up in Miles Hill and Tom's Hill schist areas 1 and 4, and the southernmost undulation develops the extensive schist areas south of Washining Lake (Area No. 6). The schist of Peck's Hill disappears south of the swamp on the north base of the elevation, but the narrower eastern fold reappears north of the swamp in Johnny's Mount and Barnard Mount, where it, too, soon disap-