Fill in the blank: Some sediment is carried along river down the and continental slope and then deposited on the Some sediment is carried along river down the and continental slope and then deposited on the . It is believed that the underwater that often lie offshore from river mouths are carved out by the movement of this . Sediment is found across in the deeper parts of the ocean basin. Some of this sediment is made up of soil and sand that are carried along the rivers from the land. Some of it is and that comes from eruptions. Some of it comes from marine life and is made up of small and the remains of . The abyssal plains on the oceans basin appear flat because they are covered in sediment, with only small rises, called being visible.