“ In the majority of folds the bending of the strata has taken place about an “axial plane” (often called the “axis”) , which in the examples illustrated in fig. 3 would pass through the points A and B, perpendicularly to the horizontal line CD. In powerfully folded regions the axial planes of the folds are no longer upright; they may be moderately inclined, producing an “inversion,” “inverted fold” or “overfold.” When the inclination of the axial plane is great a “recumbent overfold” is produced (Fr. pli couché, Ger, liegende Falte) . ”

“ Again, the most convenient site for oil wells is the crest of an anticline or “dome,” where an impervious stratum imprisons the gas and oil in a subjacent saturated layer under pressure.
For a discussion of the question of the distribution and arrangement of the great folded regions of the earth’s crust, see E. Suess, Das Antlitz der Erde, English translation. The Face of the Earth, vols. ”

“ The larger rock folds have produced important economic results. For example, in many coal regions the deposits have been conserved in some districts in the synclines or “basins,” while they have been removed by denudation from the uplifted anticlines in others. Near the crest of anticlines is commonly an enriched portion of the ground in mineralized districts; and, in the case of water supply, the tilt of the strata determines the direction of the underground flowage. ”

“ It much more frequently happens that the strata have been bent into arches and troughs, so that they can be seen dipping under the surface on one side of the axis of a fold, and rising up again on the other side. 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. The diagram in fig. 2 may be taken to represent a series of strata (1-17) thrown into an anticline (AA′) and syncline (BB′) . A section drawn across these folds in the line CD would show the structure given in fig. ”

“ The similar word for an enclosure or pen for animals, especially for sheep, and hence applied in a spiritual sense to a community of worshippers, or to the whole body of Christians regarded as Christ’s flock, must be distinguished. ”