The Lebanon Mountains are a north-south-trending range at the eastern end of the Mediterranean Sea. Investigations were conducted in this area during the summer of 1940. Because of military restrictions it was not possible to work in the northern portion of the range, and the following observations are based on field work in the southern sections.
Although Tertiary rocks occur on their margins, the Lebanon Mountains are composed wholly of Upper Jurassic and Cretaceous strata. The Jurassic is represented by Kimmeridgian and Portlandian (?) deposits; the Cretaceous by the Neocomian, Aptian, Albian, and Cenomanian. Turonian and Senonian beds have been recognized on the flanks but are absent in the central portion of the range.
All the sediments except the Neocomian are marine. The Neocomian are principally continental red sandstones with nodules of iron and lenses of lignite. Casts of plant stems are abundant, and dinosaur bones were found.
The range is bounded on both sides by prominent faults. A strong transverse fault zone runs east-west from the region of Beirut at least as far as Jebel Kenaise. North of this the range is essentially a horst of Jurassic rocks with Cretaceous deposits forming the ridges and peaks; to the south it is a tilted block with the greater uplift on the eastern side, where the Jurassic crops out, and with Cretaceous deposits dipping gently off toward the west.