Measurements at the rise pit by Malott (1932, 1952) were used to estimate that the alluvial floor of the gulf was between 10.6 m (35 ft) and 12.2 m (40 ft) thick.
During flooding, water flowing up through the rise transports sediment as coarse as granule size (2-4 mm) and deposits the particles on the margin of the rise pit adjacent to the floor (Figs.
Material deposited on the floodplain of the gulf meant future floods needed to attain higher stages to get out of the rise pit and overflow channels and onto the floodplain.