The currently accepted concepts of a Devonian unconformity and a middle Paleozoic folding phase in northwest Malaya are incorrect. At the best exposed locality of the supposed Devonian unconformity, in the Langkawi Islands, the strata from Lower to Upper Devonian are continuous, and the horizon of the "unconformity" is conformable.

Remapping in the type area of the middle Paleozoic orogenic phase shows that the deformed rocks were dated incorrectly and include strata of Ordovician to Carboniferous age. Most of the structures described in support of the folding phase are in strata of the Carboniferous Singa Formation. The age of the Langkawi folding phase is probably post-Early Permian and pre-Early Triassic.

Devonian strata containing common tentaculitid-monograptid and bivalve-brachiopod-trilobite faunas are fairly widespread in the Langkawi Islands and Kedah and Perlis States in northwest Malaya. These previously have been dated incorrectly as Silurian or Carboniferous in age.