from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A fold whereby the strata are forced through an angle of more than 90 degrees, so that younger strata lie below older ones.
from The Century Dictionary and Cyclopedia
- n. In geology, a reflexed or inverted fold; an anticlinal flexure in which the bending has been carried so far that the strata on each side of the axis have become appressed, the axial plane being bent out of the vertical, so that one limb of the fold lies upon the other.
From over- + fold, after German Überfaltung ("overfolding"). (Wiktionary)