monoclinen.

1879 A. Geikie in Encycl. Brit. X. 300/1 The strata are thus bent up and continue on the other side of the tilt at a higher level. Such bends are called monoclines or monoclinal folds, because they present only one fold, or one half of a fold, instead of the two which we see in an arch or trough.

1898 J. Milne Seismol. iii. 33 The bases of monoclines are tracts where faults are frequent.

1916 Bull. Geol. Soc. Amer. 27 92 I welcome the suggestion of the term homocline. The need of a term for this structure has long been felt in the United States Geological Survey, where confusion has been avoided in editing by using monoclinal for the homocline as distinct from monocline or monoclinal fold.

1940 E. S. Hills Outl. Struct. Geol. iv. 70 A monocline is a local steepening of an otherwise uniformly dipping or horizontal series, and is composed of an anticlinal bend above, followed by a synclinal bend at a lower level... In oil-field geology, however, the term is used for formations in which the dip is more or less uniform in one direction.

1962 H. H. Read & J. Watson Introd. Geol. I. viii. 487 In this way monoclines may be formed and may grade into zones of normal faulting.

1997 Bull. Amer. Assoc. Petroleum Geologists 81 1395/1 Thrust folds, gentle arched anticlines, stratigraphic monoclines and buried hills associated with drape anticlines are common trap styles.

1912 E. H. C. Craig Oil-finding v. 74 Oil may be obtained from monoclines, often in great quantity. In such cases the more gentle the dip, the better.

1925 A. B. Thompson Oil-field Explor. & Devel. I. v. 186 The term ‘monocline’ is here retained in its customary oil-field phraseology as representing a series of uniformly dipping beds, irrespective of the relationship they may bear to the general structure of the district.

1951 E. N. Tiratsoo Petroleum Geol. iv. 79 The monocline can be considered as virtually one limb of an anticline up which the migrating fluids pass, leaving well-marked layers of dynamically separated gas, oil and water.

1997 Bull. Amer. Assoc. Petroleum Geologists 81 1371/1 The Son Graben is a gentle northwesterly dipping monocline, in a half graben setting.