BEACHROCK DISTRIBUTION AND COMPOSITION IN TOMBOLO BEACH, MANATÍ, PUERTO RICO

A study of beachrock distribution and composition is being conducted in Tombolo Beach at Manatí, Puerto Rico, with data from 2008 to 2012. This research aims to shed light on a geomorphology research in the area that intends to use beachrocks as shoreline indicators. Beachrock in the study site exhibit diverse grain size, color, weathering stage and extension according to their location. Based on these observations, mineral composition could also vary between geographical sites. Thus, this research is essential to understanding how changes in beachrock composition and distribution may reflect beach processes. An integrated methodology that includes field work, remote sensing, and Geographic information Systems (GIS) are being used to identify beachrock characteristics in the site. Field observations, field photographs and beach profiles from previous studies are being used to evaluate the position and distribution of beachrock. Preliminary results show that some beachrocks are in the first and second stage of diagenesis, while others are found in a mature state. This evaluation may help to explore the possibility to use beachrock characteristics as an indicator to identify small-scale relative sea-level changes in the north-central area of the Island.

This research was supported by the University of Puerto Rico (FIPI), Rio Piedras Campus.