Beach Material

Beach material may come from the erosion of rocks near the beach, or be brought to the beach by rivers. Some beach sediments consist of calcium carbonate formed from the remains of corals, shells and algae. Carbonate sands are white and may be found close to coral reef sites or seagrass meadows. Such beaches are common in Tobago.

In Trinidad, the most common mineral in beach sediment is quartz. The dark colour of these sediments is due to the presence of certain iron-based minerals and rock fragments.

Grain size (Figure 2) of beach sediment is noted throughout the guide because in addition to having implications for coastal dynamics, it is one of the characteristics of a beach that is felt underfoot and, as such, one which is understood by the average beach-goer. According to the Wentworth Scale, sediments are classified as very fine (0.0625 mm to 0.125 mm); fine (0.125 mm to 0.25 mm); medium (0.25 mm to 0.50 mm); coarse (0.50 mm to 1.00 mm); and very coarse-grained sand (1.00 mm to 2.00 mm).