Tectonics and Structural Geology

foliation

Features from the Field: Chevron Folds

Samuele Papeschi June 12, 2020

Chevron folds in the radiolarites from Batain, Oman. Photo © Simon Virgo via Imaggeo

Folds are among the most strikingly beautiful structures we can observe in rocks. There are several ways folds may form in rocks. For instance, folds in sedimentary rocks may develop by liquefaction of soft sediments, but the most common way to produce folds – and also my favorite – is by deformation. When rocks are compressed by tectonic forces, layers (or foliations) bend and warp, p ...[Read More]

Features from the field: crenulation cleavage

Samuele Papeschi April 27, 2020

Crenulation cleavage in schists from the Island of Elba (Italy). Note how the older foliation is folded and a new foliation developed. Photo © Samuele Papeschi

In one of the former episodes of the ‘Features from the field’ series we have talked about foliations, and how they develop when rocks are pushed together by the movement of tectonic plates. It is quite uncommon, however, that tectonic forces are active in the same direction for an unlimited period of time. The rule, rather than the exception, is that the orientation of tectonic forces ...[Read More]