crenulation

Several foliations may be present in a rock, giving rise to a crenulation.

Crenulation cleavage is a particular type of foliation.

The posterior of these keels shows weak crenulation.

Crenulation may also be the incipient foliation plane which precipitates shearing.

A crenulation lineation has also formed which trends more or less parallel to the folds.

Crenulation cleavage contains microlithons that were folded by a previous foliation.

When the crenulation foliation begins to dominate it may totally or almost completely wipe out the original foliation.

Eventually, the crenulation foliation overprints the S1 foliation.

Crenulation cleavage occurs near these overthrusts.

The weak depressions on the sides of the crenulation pass down the sides of whorls for a short distance below the summit.

The initial impact of a crenulation foliation may be cryptic, microscopic growth of new minerals at an angle to previous foliations.

The type of crenulation cleavage pattern that forms depends on lithology and degree of deformation and metamorphism.

Recognising a crenulation in a rock may require inspecting the rock with a hand-lens or petrographic microscope in thin section.

This has been deformed with tight folds that have been overturned, and exhibits crenulation cleavage and brittle faulting.

Unfortunately, since the brains of dead people rot swiftly, we have little notion of the degree of crenulation of the Neanderthal or Cro-Magnon brain.

The angular intersection of the two foliations causes a diagnostic texture called a crenulation, which may involve folding of the earlier mica foliations by the later foliation.

There are several types of lineations, intersection lineations, crenulation lineations, mineral lineations and stretching lineations being the most common.

Crenulations, because they are the result of a second (or more) foliation, preserve important information on not only the stresses which formed the crenulation foliation, but the orientation of previous foliations.

Firstly, the crenulation must be analysed to determine the initial foliation, termed S, and the overprinting subsequent foliation, termed S. The intersection of these two planes forms an intersection lineation.

Recent styles include linen tunics edged with a crenulation motif you'll recognize from Koutoubia Minaret and well-lined sabra (cactus silk) slippers without the recently-tanned scent you'll find in shops closer to the tanneries.

In this case, it s often likely that the crenulation acts as a shear plane and it may be difficult to reconstruct earlier foliations and rock units across the crenulation foliation.

In more brittle conditions, especially in highly micaceous rocks, a crenulation may appear as kink bands, where S1 foliations are kinked by the S2 foliation so that the original minerals are broken or deformed.

Crenulation or Crenulation cleavage is a texture formed in metamorphic rocks such as phyllite, schist and some gneiss by two or more stress directions resulting in superimposed foliations.

This is not proof in itself that our ancestors were more intelligent than we are: it seems that the ability of a brain depends less on its size than on the extent of its complexity, as epitomized by the degree of crenulation (folding) on its exterior.

This process occurs at different rates in rocks and beds of different lithology and chemical composition so that it is usually valuable to look at a variety of outcrops to gain a better appreciation of the effect of crenulation or discover the orientation or presence of earlier foliations.