**3. Geology of the region**

It is believed that the mud beach coast evolved from the growth of the Niger delta into the Gulf of Guinea following the gradual retreat of the sea after a short-lived Paleocene transgression [1]. The major geological formations in the area include general alluvium, lagoonal marshes, abandoned beach ridges and coastal plains sand. The general alluvium comprises coarse, clayey, unsorted sands with clay lenses and occasional pebble beds which are lithologically indistinguishable from typical coastal plains sand strata [6]. These formations produce generally swampy soils on the nearly level coastal plains sand on alluvium, and very deep, well-drained soil, with very dark brown to dark brown surface sands from the nearly level coastal plains on coastal plain sand [7]. Elevation rises from about 1 m along the coastline to between 35 m (Igbokoda town) and 55 m (Okitipupa town) in the upland [8].
