Data for: Pre-vegetation, single-thread rivers sustained by cohesive, fine-grained bank sediments: Mesoproterozoic Stoer Group, NW Scotland

The Silurian-age shift in fluvial stratigraphic architecture is associated
with the predominance of shallow pancontinental braidplains in the
vegetation-free, pre-Silurian period. Recognition of deep, single-threaded
channels in pre-Silurian strata challenge this paradigm; however, it is
unclear how these rivers sustained stable banks. Here, we combine
measurements of fluvial cross-strata from the 1.2 Ga Stoer Group with
quantitative paleohydraulic tools to reconstruct river geometry and
planform. We show that the deposits are consistent with deep (4-7 m),
low-sloping rivers (5.6x10-4 to 4.5x10-5), similar in morphometry to
modern single-threaded rivers. We show that mud in floodplain sediments
provides sufficient resistance to erosion to withstand the reconstructed
bank shear stress, indicating that sediment cohesion from mud alone can
foster deep pre-Silurian rivers. We suggest that the apparent
stratigraphic shift coeval with the greening of continents marks a
kinematic change in channel migration rates rather than a geometric shift
in river planform.