. The building of an island : being a sketch of the geological structure of the Danish West Indian island of St. Croix, or Santa Cruz. Geology -- Virgin Islands of the United States Saint Croix. 48 THE BUILDING OF AN ISLAND. But the two sets of strata do not dip away at right angles to the axis but in a sloping direction on each side (Fig. 20), and we must ask, how is this to be explained ? For an explanation we may fall back on an earlier result of our investigations. In our study of the limestone formation we saw that some of the lines marking the divisions between sets of limestone strata h
. The building of an island : being a sketch of the geological structure of the Danish West Indian island of St. Croix, or Santa Cruz. Geology -- Virgin Islands of the United States Saint Croix. 48 THE BUILDING OF AN ISLAND. But the two sets of strata do not dip away at right angles to the axis but in a sloping direction on each side (Fig. 20), and we must ask, how is this to be explained ? For an explanation we may fall back on an earlier result of our investigations. In our study of the limestone formation we saw that some of the lines marking the divisions between sets of limestone strata having differ- ent dips ran across other lines, indicating that the forces of elevation acted in two directions, crossing each other, though perhaps not exactly at right angles. We saw, for instance, that the limestones of the great Synclinal of the Central Slope do not dip at right angles to the axis but come down to it from the northeast on one side and from the northwest on the other, indicating a cross- elevation from the north. Fig. And, what has a more tlirect bearing on the case before us, we saw in" re- gard to the anticlinal of the Mt, Eagle Ridge that as we followed the axis from the ridge across the plain and down the Barren Spot Valley the strata on . either hand passed away to southeast on the one side and to south-by-west on the other, not by any means at right angles to the axis, but with a southerly inclination which could onlv be explained bv supposing that there was also a tilting from the north. So in the larger case we are now considering, we have onlv to suppose that besides the pressure from the north-northeast which pushed up the ancient strata into a great fold (or into folds, as we shall see later), there has been another force acting from a line of elevation to the west which has given the sloping direction of the dips on both sides of the anti- clinal. When studying the Mt. Eagle anticlinal, the fust which we met with in our investigations, w
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