CE6301 ENGG GEO Notes, Engineering Geology Lecture Handwritten Notes – CIVIL 3rd SEM Anna University

PETROLOGY

All rocks that have formed from an original hot, molten material through the process of cooling and crystallization may be defined as Igneous Rocks.
2. Define about Hypabyssal Rocks
These Igneous Rocks are formed at Intermediate depths, generally up to 2 Km, below the surface of earth and exhibit mixed characteristics of volcanic and plutonic rocks. Porphyries of various compositions are example of Hypabyssal Rocks.
3. Define Texture of Igneous Rocks
The term texture has been defined as the mutual relationship of different mineralogical constituents in a rock. It is determine by size, shape and arrangement of these constituents within the body of rock.
4. What are the factors Explaining Texture?
a) Degree of Crystallization Holocrystalline, Holohyaline.
b) Granularity Coarse grained, Medium grained, Fine grained. c) Fabric Panidiomorphi, Allotrimorphic, Hypidiomorphic.
5. Define Equigranular and Inequigranular Texture
All those textures in which majority of constituent crystals of rock are broadly equal in size are described as equigranular textures. All those textures in which majority of constituent minerals show marked difference in their relative grain size are grouped as inequigranular extures.