CHARACTERIZING SHORELINE PROCESSES IN BARNACLE BEACHES: THE SALTON SEA, CALIFORNIA

Beach sedimentation processes vary depending on environmental conditions. The Salton Sea, located in the interior arid region of southern California, is a unique lacustrine shoreline composed largely of transported barnacles. Currently, barnacles thrive in the Salton Sea’s hypersaline conditions. Barnacle growth clusters are broken off their substrate, most likely by storms, and transported shoreward. This unique barnacle accumulation is the only known lacustrine, barnacle-dominated shoreline and possesses some surface features that are exclusive to this beach setting.

We measured topographic profiles and collected grain size percentages from eight locations at the Salton Sea. The beaches are orientated approximately north-south along the north-eastern shore. Here, wind and storm events produce the highest waves and sedimentation rates forming beaches approximately 64m wide. The average and maximum ridge slopes are 0.098 and 0.16, respectively. The slopes of these beaches from water level to back beach average 0.031. The largest sediment grains (articulated barnacle clusters) dominate the surface of the beaches at and near lake level. Preliminary bulk density calculations of the barnacles average 0.52 g/cc. This low-bulk density gives the beach a unique mantle of articulated barnacle clusters near the shoreline. Ultimately, these mantle deposits are reworked to a thickness of up to 2m in some locations. From the shoreline to the back beach area, there is a decrease in articulated and an increase in fragmented barnacles. The barnacles are transported according to a series of shore processes including storm-wave action producing wash-overs and longshore drift. Landward dipping cross strata characterize wash-overs with the cross strata made up of finer-grained sediment fluctuating between mixed amounts of sand, silt and fragmented barnacles. Internal beach ridges have lake-ward dipping cross strata composed of single and fragmented barnacles with minor sand component. Combined, this data provides a picture of a rapidly deposited, barnacle dominated lacustrine beach setting.