Baclayon Uplifted Marine Terrace
The uplifted marine terraces in Baclayon is a similar landform to the more recently uplifted marine terrace in Maribojoc. However, the terraces in Baclayon are much older. It was formed during the Pliocene-Pleistocene time (5 million years – 10,000 years ago). Fault movement along the coast caused the uplift of formerly underwater reefs raising it at a height above the sea and creating a marine terrace along the coast. Several other subsequent fault movements shaped the successive step-like characteristics of the marine terraces seen at Baclayon. The three-step terraces there stand at 20 meters, 40 meters and 60 meters above sea level signifying at least three episodes of progressive tectonic uplift area. The ancient marine terraces can be observed in the step-like quality of uphill roads that branches inland from the highway in Baclayon.
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The uplifted marine terraces in the vicinity of Baclayon town is much similar to the uplifted marine terraces in Maribojoc. However, the uplifted marine terraces in Baclayon were much older; it was formed during the Pliocene-Pleistocene time (5 million years – 10,000 years ago). A marine terrace is an emergent coastal land. A marine terrace is an emergent coastal landform that was raised at a height above the sea level, and in turn causes a relative fall in the sea level. Tectonic coastal uplift and sea level fluctuations (not tidal) resulted in the formation of these marine terraces.
Three terraces with elevations 20 meters, 40 meters and 60 meters above the sea level are observed in the area, which indicate intensive series of tectonic uplift that occurred along the southeastern coast of the island. Similar process that formed the Maribojoc-Loon uplifted coast caused the formation of the landform found in the town of Baclayon. During the Plio-Pleistocene, vertical tectonic movement triggered the uplift of the underwater reefs. There were three evident episodes of uplift that occurred in the area as indicated by the step-like appearance of the 20m, 40m and 60m terraces above sea level.
Fragments of large and thick shells (Tridacna gigas) and fragments of the gastropod group Strombaceae, have been collected by Hillmer and Scholz (1986). Two terraces in Baclayon were tested using the Uranium-Throrium Analysis to identify the age when the terraces were uplifted. Based on the data gathered, the terrace with an altitude of 20 meters is +/- 129,000 years old, and the terrace with an altitude of 60 m is +/-310,000 years old.