Taking the Atlantic as our simplest type, we may say that the surface of an ocean basin resembles that of a mighty trough or syncline, buckled up more or less centrally in a medial ridge, which is bounded by two long and deep marginal hollows, in the cores of which still deeper grooves sink to the profoundest depths.
The group of heights of South Wales, running on the whole from west to east, marks the outcrops of the Old Red Sandstone and Carboniferous strata which lie within a vast syncline of the Silurian rocks.
Where they dip away from the axis of movement the structure is termed an anticline or anticlinal fold; where they dip towards the axis, it is a syncline or synclinal fold.
(I-17) thrown into an anticline (AA') and syncline (BB').
13, which, instead of passing here under the next in order, turns up with a contrary dip and forms the centre of a trough or syncline (B).
Hence the anticline noses out to the north and the syncline to the south.
In describing rock-folds special terms have been assigned to certain portions of the fold; thus, the sloping sides of an anticline or syncline are known as the "limbs," "slopes," "flanks" or "members" of the fold; in an anticline, the part X, fig.
Charniere anticlinale), the corresponding part of a syncline being the "trough-core" or "base," Y, fig.
The crest-line of an anticline or trough-line of a syncline is rarely horizontal for any great distance; its departure from horizontality is designated the "pitch," and the fold is said to pitch (or dip) towards the north, &c. Most simple folds - with the exception of very shallow curvatures of wide area, - when considered in their entirety, are seen to be somewhat canoe-shaped in form.