Glomar Challenger at the Cretaceous–Tertiary boundary

Calcareous Nannofossils across the K/T Boundary|ODP Hole 690C|Maud Rise|Weddell Sea

“…The K/T section at Site 690 also displays the great depth range achieved by some burrowing organisms. Generally, in the deep sea, the effects of bioturbation are thought not to exceed 40 cm and to average in the range of 10-20 cm (Wright et al, 1982;Smit and Romein, 1985). It is apparent here that this range needs to be expanded, almost tripled in this case.…”