The main factors influencing the distribution of geomorphic
features in the Assynt area are geology and the location of Loch
Lomond Advance glaciers. A study of glacial striae and erratics has
enabled the construction of a model for the development of the last
ice sheet. Glaciers developed in the corries on the N and E side of
the Assynt mountains, coalesced and thickened until an ice divide was
established, ice overtopping the mountain ridge to flow both eastwards
and westwards; the ice divide was always situated to the E side of
the mountains. Even the highest parts of the study area were covered
by ice to a considerable depth. An early deglaciation of the area is
suggested by a radiocarbon date of 18,040 240 years B.P. from
fragments of reindeer antlers. Reconstruction of the seven Loch
Lomond Advance glaciers that subsequently formed in the area has
shown that the main snow -bearing airstreams came from the south and
that the blowing of snow onto glaciers surfaces was a major factor in
Glacial friction cracks are widespread in the Assynt area. A revision of nomenclature and a simplified classification is suggested.
Attempts have been made to characterise certain Assynt friction crack
forms, and orientation studies suggest that they are useful ways of
establishing the former ice flow direction when striae or ice -moulded
bedrock are absent, as long as a large number of them are measured.
Their orientation is sometimes affected by weakenesses in the bedrock.
A study of the caves in the Cambrian dolomite of the area indicates that they originated phreatically, but subsequent lowering
of the local water-table has tended to result in high-level,
abandoned passages, often choked with clastic deposits, and lower - level passages containing the active streamways. Clastic cave
sediments are largely allochthonous, being derived from local glacial
deposits. The dating of certain calcite speleothems has shown that
many of the main elements of the subterranean drainage network were
in existence prior to the last glaciation, and some parts may predate the penultimate interglacial. The Creag nan Uamh caves have
yielded a unique Devensian and Flandrian fauna, and also evidence
for the earliest recorded existence of man in Scotland, dated by
radiocarbon to 10,080 70 years B.P.