Mapping modern and paleo-grounding lines around the Antarctic Ice Sheet
elucidates processes occurring at the grounded ice-ocean interface.
Positional differences across individual grounding lines manifest as
longitudinal (plan-view) grounding line sinuosity. We explore the causes
and significance of such sinuosity by coupling observations of
contemporary Antarctic grounding lines and paleo-grounding lines
expressed as ice-marginal landforms, specifically focusing on the role
that bed topography may play in influencing grounding-line sinuosity.
For equal-length grounding-line segments, modern and paleo-grounding
lines have remarkably similar sinuosity distributions, with the vast
majority of grounding lines being near linear. Surprisingly, grounding
line sinuosity is highest on low sloping beds and lower on rougher beds,
even for grounding lines that are clearly pinned on topographic highs.
For contemporary grounding lines, sinuosity is higher and more variable
for grounding lines near floatation with shallow height-above-buoyancy
gradients. We argue that grounding line sinuosity is a product of the
combined influence of height-above-buoyancy gradient, bed slope, and bed
roughness and, perhaps counterintuitively, that this relationship does
not appear to be sensitive to the presence of pinning points, ice-flow
speed, or the presence/absence of an ice shelf.