rift

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Related to rifting: rift valley, Rift basin

rift

1
Geology a long narrow zone of faulting resulting from tensional stress in the earth's crust

rift

2 US
1. a shallow or rocky part in a stream
2. the backwash from a wave that has just broken

Rift

 

a major linear tectonic structure of the earth’s crust hundreds and thousands of kilometers long that forms when the crust is horizontally extended; this process usually occurs where there is a vast arching uplift. It is believed that the entire thickness or a significant part of the thickness of the earth’s crust is being extended.

A rift consists mainly of a series of fractures, among which faults with inclined surfaces predominate; the crustal sector lying above the surface of a fault is also dislocated downward. The sum of the horizontal components of all such shifts compensates for the horizontal extension of the crust. The dip of a fault is usually 60°-70°, and the vertical amplitude of the shift along a fault may reach 5 km. The crustal extension can be several kilometers, and in some cases, several tens of kilometers long.

Various types of grabens and horsts are found within a rift. The graben is the chief structural form. A rift usually begins to form, however, with a gentle upward bend of the crust in the form of a tectonic arch; the arch later breaks up and separates into grabens and horsts. Very large rifts are called rift zones or systems.

V. V. BELOUSOV

rift

[rift]
(geology)
A narrow opening in a rock caused by cracking or splitting.
A high, narrow passage in a cave.

rift

The direction in which stone splits most readily; characteristic of granite or other stone not having visible stratification or foliation.
References in periodicals archive ?
Is the thoroughly-studied Iberia--Newfoundland margin the best example for learning about rifting processes that lead to seafloor spreading?
The age and style of rifting sets the collisional template, defining the shape of the rifted margin (salient-reentrant geometries) and the thermal age (strength) of the margin, similar to younger orogens.
88 Ga) magmatic-oceanic component related to rifting that seems to be concentrated along the continental margin of the Superior craton and may have been related to a plume impinging on the underside of the rifted Superior lithosphere.
Scant evidence is available on the nature, style and timing of early rifting within the Superior Province.
This is overlain by voluminous tholeiitic basalt and minor komatiite (2740-2700 Ma), probably indicating rifting and/or plume activity, at a scale comparable to that of modern large igneous provinces.
A fourth end member, such as rifting, could be added, and "plume" was suggested to describe one possible non-subduction-related process.
So if there was a megabank," he says, "it would have been at least of late Jurassic age [about 150 million years], much older than originally porposed, and that's getting close to the time of rifting.