Figure 2.

(a) Colour-contoured bathymetry map of Mariana Trench area (small red box at ∼12.5°N, 147°E in figure 1), lit from northwest (cool/dark colours are deep, warm/light colours are shallower). White asterisks show positions of ROV Dives 4 [1] and 16 [1] at approximately 20°N. Black dashed line is Mariana Trench axis. (b) ROV video grab of oblique view of reef sequences on ROV Dive 4 on the deep inner slope of Mariana Trench (light layers are massive reef deposits (rudists, figure 3), darker layers are mainly bivalve fossils). Debris chutes and intervening sharp ridges are from submarine mass-wasting. (c) ROV video grab of oblique view on ROV Dive 16 of Cretaceous reef sequences on Pacific Plate Cretaceous guyot, light layers are massive reef deposits and rudists ( figure 3 for scale) and darker layers are mainly bivalve fossils. (Online version in colour.)