At http://phys.org/print308905318.html … we learn of a massive sub glacial trough, deeper than the Grand Canyon, in Antarctica. The British Antarctic Survey, based in the West Antarctic peninsular, were charting a mountain range below the ice (using satellite image data and ice penetrating radar towed behind skidoos or on board small aircraft). Sounds like a good job – and it is ongoing. The trough is so deep it effectively cuts the peninsular in half – making the upper bit an island (as far as sea level is concerned). The ice keeps it as a complete unit and the trough was never expected – even though we had horror stories about all the ice melting. The mapping of West Antarctica continues but the subglacial valley is 3km deep and over 300km in length – and at some points some 25km in width. A substantial geological structure.