Ystyr 'flute' yma yw 'rhigol': fe lenwir y rhigol gan waddodion llaid sy'n
caledu a ffurfio 'gwrym' yn siap y rhigol. Awgrymaf 'gwrym rhigol'
(lluosog, gwrymiau rhigolau).
Bruce
----- Original Message -----
From: "Sian Roberts" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, December 13, 2006 3:09 PM
Subject: flute cast
Flute cast: (geology) A raised, oblong, or subconical welt on the bottom
surface of a siltstone or
sandstone bed formed by the filling of a flute.
a
Flute casts are irregular ridges that display a marked asymmetry. The
asymmetry of these structures
allows for determination of paleocurrent direction-flows originate from the
direction of the steeper
side of the flute. Flute casts typically have a "pointy" end, oriented in
the upstream direction, and a
more gentle, flared end that merges downstream into the bed surface. Flute
casts along the base of
a given bed are usually of approximately the same size, but between beds or
formations, may vary
greatly in size.
Byddwn yn ddiolchgar am unrhyw gymorth.
Siān
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