Channels towards the top of the Etive Formation

Towards the top of the Etive Formation small-scale
fining-upwards channel successions are characterised
by cross-beds (facies 11a) and by sandstone with marine
trace fossils (facies 17). Following the arguments
presented above, these channels are unlikely to have
formed in a fluvial or in a shoreface setting. They
may have developed at the landwards side of a tidal
inlet, or in a tide-influenced distributary system.

Units within the Ness Formation are commonly
characterised by an upwards cleaning and coarsening
succession of sandstones that either abruptly, or gradationally
overlie shales of facies 2 or facies 15. The
sandstones are dominated by flaser and linsen, and
bioturbated facies (facies 16 and 17, respectively).
Cross-stratified sandstone (facies llb) arranged in
small-scale fining-upwards successions may overlie
these facies.
This facies association is interpreted as the deposit
of a mouth bar in a bay head delta. The flaser
and linsen, and cross-stratified deposits record an
axial position on a wave-influenced mouth bar. By
contrast, the bioturbated sands represent a lateral
mouth bar location. Abruptly based sandstones may
reflect autocyclic channel switching, or small-scale,
base-level falls.