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Summary of Geology.

The Yong Peng area is bounded by latitude 1 49'N to 11'N, and longitude 102 59'E to 103 15'E, covering an area of approximately 1,230 km. The study area is located in the low-lying western-central part of Johor.

The Upper Permain Dohol formation that was deposited in a marine environment is the oldest rock unit in the study area. The formation consist mainly of shale, siltstone, pyroclastic rocks, and minor limestone which had undergone low grade metamorphism. The rocks are folded due to compression from more than one orogeny phase, and are well exposed in the eastern part of the study area.

Deposition of the Semantan Formation took place during the Middle to Late Triassic. The formation that occupies most of the southeastern, central and northern parts of the study area comprises shale. siltstone, mudstone, tuff, and some sandstone. Semantan Formation is underlain unconformably by the Dohol formation.

Igneous instrusion in the Yong Peng area took place during the Late Triassic, i.e. after the deposition of the Semantan Formation was completed. There are two groups of instrusive rocks, namely the Soga Granite and the Bekok Granite occupies the northeastern part.