He continued his work in the Boulder Batholith and investigated intrusive igneous rock bodies in the Spanish Peaks in Colorado.
12.
A batholith is a body of intrusive igneous rock formed by the cooling of magma under the Earth's surface.
13.
Three types of geological formations are found in the area : intrusive igneous rocks, metamorphic rock and formations from more recent volcanic eruptions.
14.
"' Granite "'( ) is a common type of felsic intrusive igneous rock that is granular and phaneritic in texture.
15.
Technically speaking, an intrusion is any formation of intrusive igneous rock; rock formed from magma that cools and solidifies within the crust of the planet.
16.
Intrusive igneous rocks that form at depth within the crust are termed plutonic ( or " abyssal " ) rocks and are usually coarse-grained.
17.
Intrusive igneous rocks that form near the surface are termed " subvolcanic " or " hypabyssal " rocks and they are usually medium-grained.
18.
The extrusive and intrusive igneous rocks are underlain and intruded by a series of I-type granite intrusions and granite domes of c . 2.65 Ga age.
19.
The term " granitic " means granite-like and is applied to granite and a group of intrusive igneous rocks with similar textures and slight variations in composition and origin.
20.
"Phaneritic " ( " phaner " = visible ) textures are typical of intrusive igneous rocks, these rocks crystallized slowly below Earth's surface.
