Stratigraphy: Devonian sedimentary rock with an age ranging from 417 to 354 million years before present - the oldest rock outcrops in Hong Kong.

Distribution: The Bluff Head Formation is present from Bluff Head to Harbour Island, Ma Shi Chau and Ma On Shan areas, northeastern New Territories.

Lithology: The Bluff Head Formation consists of pale grey, fine- to coarse-grained quartz sandstone and reddish brown purple siltstone with greyish white, quartz-pebble conglomerate.

Depositional Environment: The majority of the Bluff Head Formation represents the deposits of fluvial channels. Minor facies include sheet flood, aeolian, paleosol and deltaic facies associations.

(Quartz-pebble conglomerate of the Bluff Head Formation at Fung Wong Wat, Tolo Channel, northeastern New Territories)