Glacial moraines are not well sorted. As a sediment matures, it becomes more well sorted, with larger particles settling out and finer particles being moved on. The Hjulstrom curve shows the relationship between current velocity and particle size and erosion, transportation and deposition. They either settle out in estuaries, become part of deltas or are spread across the shelf by currents. Most of this process is by longshore currents caused by breaking waves.
Glacial transport is of importance in subpolar regions.
Clay particles require high currents speeds to erode or resuspend them due to their flat shape and high cohesiveness. They have a high surface area to volume ratio. Think to squirting a piece of clay with a hose. Wind transport acts on particles less than 20 microns and can carry them out into the open ocean. A second source of this sediment type is volcanoes, both terrestrial and undersea 2.