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The land mass that is now Arran has wandered across the
face of the earth through varying latitudes and in different geological
settings. The rock types found on Arran reflect the latitude of the land mass
at the time of their deposition or formation and the geological conditions
that prevailed at that time, as well as forces that may have acted on them
after their deposition. These pages are based in part on information
contained in
McKerrow
and Atkins, 1989 , MacDonald and
Herriot, 1983 and Gunn 1903 and
references there in, and from field observations by Arran Heritage Museum
Geological Volunteers. Any mistakes are truly of the volunteers own making!
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The main rock types found on Arran were formed
during the Cambrian Period (590-505 million
years ago or Ma), the Ordovician
Period (505-438 Ma) , the Devonian
Period (408 -360 Ma)
, the Carboniferous Period (360-286
Ma), the Permian Period (286-248
Ma), the Triassic Period (248-213 Ma) and
Tertiary Period (65-2 Ma), see the simplified
geological map below for their distribution. There are also some special
outcrops of rocks formed during the Jurassic
( 213-144 Ma)
and Cretaceous ( 144-65 Ma) periods. There are no rocks
on Arran from the Pre-Cambrian (4600- 590 Ma) and the
Silurian (438-408 Ma) periods.
There are wonderful examples of moraines and glacial tills, as well
as beautiful U-shaped and hanging valleys produced during the
Quaternary Period (2 Ma to
present).
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Click on the links in the text above or on the page below
to see some examples of the rock types formed during a specific Geological
Period found on Arran, and for some overview of the geological processes
occurring on Arran and the surface of the earth during that Period. Click on
the Cambrian Period button on the top left hand side of this page to begin
moving through the examples in chronological order.
The Cambrian Rocks of Arran
The Ordovician Rocks of Arran
The Silurian Period on Arran
The Devonian Rocks of Arran
The Carboniferous Rocks of Arran
The Permian Rocks of Arran
The Triassic Rocks of Arran
The Jurassic Rocks of Arran
The Cretaceous Rocks of Arran
The Tertiary Rocks of Arran
The Quaternary Period on Arran
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