Formation. A group, whether of alluvial deposits, sedimentary strata, or igneous rocks, referred to a common origin or period.
Fossil. All minerals were once called fossils, but geologists now use the word only to express the remains of animals and plants found buried in the earth. Etym., fossilis, any thing that may be dug out of the earth.
Fossiliferous. Containing organic remains.
Galena. A metallic ore, a compound of lead and sulphur. It has often the appearance of highly polished lead. Etym., γαλεω, galeo, to shine.
Garnet. A simple mineral, generally of a deep red color, crystallized; most commonly met with in mica slate, but also in granite and other igneous rocks.
Gasteropods. A division of the Testacea, in which, as in the limpet, the foot is attached to the body. Etym., γαστηρ, gaster, belly, and ποδα, poda, feet.
Gault. A provincial name in the east of England for a series of beds of clay and marl, the geological position of which is between the Upper and Lower Greensand.
Gavial. A kind of crocodile found in India.
Gem, or Gemmule, from the Latin gemma, a bud. The term, applied to zoophytes, means a young animal not confined within an envelope or egg.