Final answer:
The thickness of clay and other sediments is greatest near the shore, where they are transported from continents by rivers and wind. Further away from the shore, finer sediments like clay accumulate slowly in deep marine environments, especially in sloping areas like continental margins.
Step-by-step explanation:
The thickness of clay and other sediment is greatest near the shore. This is because sediments like muds, silt, and clay are brought to the coastal areas by rivers and wind currents from the continents. Moreover, sediments in the marine environment are distributed according to their size and weight, with heavier and coarser materials such as sand settling closer to shore, while finer particles like silt and clay settle further away. In deep marine environments, sedimentation rates may be slow, but over time can result in very thick accumulations of fine-grained sediments like clay, particularly if there is a consistent supply from continental sources.
Additionally, the nature of sediment deposition means that in areas where the underlying surfaces are sloping, such as continental margins, sediments can accumulate to greater thicknesses. These sloping strata are reflected in the slope of sediment layers called clinoforms. In such environments, the sediment layers will conform to the underlying slopes until they reach the maximum angle of repose.