Stratigraphy: Cretaceous volcanic rocks with an age of approximately 142.7 ± 0.1 million years before present.

Distribution: The Ngo Mei Chau Formation occurs only in the northeast New Territories, and is exposed chiefly on Kat O Chau and Ngo Mei Chau in the northwest of Mirs Bay.

Lithology: Dominantly eutaxitic fine ash tuff with minor intercalated siltstone and mudstone.

(Eutaxitic fine ash vitric tuff of the Ngo Mei Chau Formation, Ngo Mei Chau, northeastern New Territories)