MOUNTAIN

TWO SISTERS G A >

f

ys

Spectacle Lokes

FLAT TOP MOUN TAIN

MOUNTAIN PINEGROVE Y A MOUNTAIN =

¥ ZAWINGDAM at

SOVEREIGN Se MOUNTAIN

\ Sa 4 ing 4a, a Si

7

mn A | ge g MOUNTAIN Ss )) ew,

Little

(aM islbay.

sya

Figure 50. Maps of the Barkerville Terrane divided into arbitrary structural domains marked by black dashed lines. The equal area nets are plots of A) fold axes of the shear folds for each of the domains and B) ductile folds for each of the domains. Note the diversification of the fold axes attitudes to the southwest of the Lightning Creek Anticlinorium.

Lake. Bowman (1889) first described it; and subsequently, Johnston and Uglow (1926), Holland (1948, 1954), Sutherland Brown (1957), Campbell et al. (1973) and Struik (1982a, b). All suggested that the structure was an anticline.

The antiform folds the regional foliation, is symmet- ric and changes along trend from a broad arch to an open fold. It is intersected with a widely spaced axial surface cleavage where the hinge of the fold is tightest. Folds flanking the anticlinorium verge toward its axis (Fig. 49).

70

The extent of earlier folds that were folded by the anti- form are unknown. Earlier I (1982a) speculated that the antiform may fold recumbent east-verging folds with limbs on the order of 4 to 8 km long, but such specula- tions depend on a thorough understanding of the strati- graphy, something not yet attained. Because the antiform folds the regional cleavage, it is assumed that it folds the isoclinal folds associated with that cleavage.

Campbell et al. (1973) and Struik (1981) described the cleavage of the antiform as arching through its hinge,