11. Ninnis fell through a crevasse, and his body weight is likely to have breached the snow bridge covering it. 12. Climbers normally go around it or cross one of the snow bridges that naturally form across the gap, he said. 13. Wisting later recalled how his sledge, with Amundsen aboard, nearly disappeared down a crevasse when the snow bridge broke underneath it. 14. Snow bridges are fastened to the slope on the upslope side by tension anchors and on the downslope by compression anchors.15. Cook's east face, when he fell eight meters ( 26-foot ) into a crevasse when a snow bridge collapsed on Wednesday. 16. A crevasse may be covered, but not necessarily filled, by a snow bridge made of the previous years'accumulation and snow drifts. 17. Climbers normally go around it or cross it on one of the snow bridges that naturally form across the gap, he said. 18. At the base of the descent, a 1 2-metre-wide crevasse runs end to end, and there are a couple of snow bridges . 19. Occasionally a snow bridge over an old crevasse may begin to sag, providing some landscape relief, but this cannot be relied upon. 20. Climbers normally go around it or cross it on one of the snow bridges that naturally form across a gap, he said.
