Rather than collecting material for dating evenly spread across the entire area covered by the ice sheet we developed a sampling scheme driven by;
- Our focus on reconstructing ice retreat across the marine-to-terrestrial transition. Retreat of marine-influenced ice margins is difficult to understand because buoyancy on the ice margin (yielding floating components -tongues and shelves) and heating from the ocean introduces extra physics over the simpler case of mostly just surface ice melting which controls terrestrial margins.
- An understanding that bed topography plays an important control in modulating margin retreat rates through variations in outlet trough width and depth. Overdeepenings and reverse-bed slopes for example are thought to impart unstable behaviour on margin retreat.
- The existing map of ice margin retreat, which is used as a sampling framework whereby dates fixed at specific sites can be interpolated across wide distances using the landform record of margin positions
- The database of existing dated sites, revealed the ‘blanks on the map’.
- A strong motivation to treat offshore and onshore ice retreat in an integrated manner, rather than the more typical approach where these are dealt with in separate projects.
From these drivers we chose build our sampling framework and project organisation around eight transects each tracking retreat from the edge of the continental shelf until the margin back-stepped onshore for a few tens of kilometres. Here you can see our 8 transects, each led by a key scientist responsible for synthesising and interpreting both the marine and terrestrial elements.
Original proposed transect map
Revised transect map on completion of sampling programme, Summer 2015