In this chapter we will meet pioneer marine geologist Francis ShepardFrancis Shepard and learn how submarine canyonsSubmarine canyon are formed by underwater land-slides and turbidity currentsTurbidity current. Submarine canyons incise the continental slopeContinental slope of all the worlds continental margins; around 10,000 large canyons have been mapped globally. The largest canyons have heads that incise the continental shelf and in some cases connect directly to large river systems. However, most smaller canyons do not incise the shelf and are found to be confined entirely to the continental slope; so-called “blind” canyons. This observation leads to the conclusion that most canyons are initiated on the continental slopeContinental slope and evolve through retrograde slope failureRetrograde slope failure; turbidity currentsTurbidity current may occur but they only become a major factor in canyon development after the canyon head has breached the shelf break such that the canyon is able to intercept sediment mobilised on the shelf.