The coastal zone of Tuxpan-Tampamachoco, Ver., Mexico.

Between 20° 18' and 21° 02' north latitude and 97° 19' and 97° 22' west longitude. 1,500 Ha. Type II origin. Differential terrigenous sedimentation. Coastal lagoons associated with fluvial deltaic systems produced by irregular sedimentation or surface subsidence causing compaction of the load effects. They were formed and several have been modified during the last 5 thousand years; some others are very young geologically (hundreds of years). Sandy barriers form rapidly, enveloping very shallow marginal or intradeltaic depressions; low sediment input deltas may be shallow and often ephemeral, elongated lagoons between beach mounds. They are frequent along the deltaic planes of the Gulf of Mexico regions. Barrier deltaic depression. Barriers of various types; mud, sand, mangroves, etc.; runoff usually direct from rivers and tributaries; slow modifications of shape and bathymetry occur, although some become rapid; energy typically very low, except in channels; salinity is very low, but may vary with river discharge. Climate: Ax' (w1) (e) w''.