The term slickenside, although it might suggest only the planar surface,
applies to the whole feature. Years ago a former lecturer of mine wrote a
learned paper in which he tried to coin the name slickenstriae for the
striations - I don't think it ever caught on, at least it's not in common
usage.
Serpentine certainly develops polished surfaces quite readily, I suspect
this is a function of the soft, and generally homogeneous nature of the
material. One might reasonably expect a harder rock to crumble and have a
less readily polished character.
Regards
Ian Hodkinson
----- Original Message -----
From: "Martin Critchley" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, April 22, 2009 2:38 AM
Subject: Re: Slickensides
Slickensides are caused by the two walls of a fault (or a mineral vein)
moving past each other due to stress in the Earth's crust.
Irregularities (or bumps) on the two walls grind past each other due to
movement along the fault. This often results in both a polished surface
of the fault plane and striations due to the gouging effect of the
irregularities or bumps on the fault plane.
The slickensides/striations are an indication of the motion on the fault
plan (eg vertical, horizontal or oblique). Some people say that they
can also tell the direction of the motion (up or down, left or right) by
feeling the roughness/smoothness of the slickensides in one direction.
However, faults may have undergone several different types of motion
during their lifetime and slickensides may only be the indication of the
last phase of movement.
Martin
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