Magma or lava is the molten form of rocks where intense heat turns them into hot magma. This is semi fluid and is in the subsurface. This magma can come out and produce lava and this also intrude in the joints or into the parent rock which is called dykes or sills. Igneous rocks are of two types according to the place where they forms i.e. intrusive and extrusive.
Carbonate Petrography
Carbonate petrography is the study of limestones, dolomites and associated deposits under optical or electron microscopes greatly enhances field studies or core observations and can provide a frame of reference for geochemical studies.
25 strangest Geologic Formations on Earth
The strangest formations on Earth.
What causes Earthquake?
Of these various reasons, faulting related to plate movements is by far the most significant. In other words, most earthquakes are due to slip on faults.
The Geologic Column
As stated earlier, no one locality on Earth provides a complete record of our planet’s history, because stratigraphic columns can contain unconformities. But by correlating rocks from locality to locality at millions of places around the world, geologists have pieced together a composite stratigraphic column, called the geologic column, that represents the entirety of Earth history.
Folds and Foliations
Geometry of Folds Imagine a carpet lying flat on the floor. Push on one end of the carpet, and it will wrinkle or contort into a series of wavelike curves. Stresses developed during mountain building can similarly warp or bend bedding and foliation (or other planar features) in rock. The result a curve in the shape of a rock layer is called a fold.
Igneous rocks
Magma or lava is the molten form of rocks where intense heat turns them into hot magma. This is semi fluid and is in the subsurface. This magma can come out and produce lava and this also intrude in the joints or into the parent rock which is called dykes or sills. Igneous rocks are of two types according to the place where they forms i.e. intrusive and extrusive.
Metamorphic rocks
These rocks forms mostly where magma chamber is available to heat enough for mineralogical changes occurrence. These rocks have multiple features in distinguishing like schistosic, gneissic and slaty texures.
Texture is the physical character or a pattern.
Slaty texture
Schistose
Gneissic
Sedimentary rocks
Sedimentary rocks
- clastic
- non clastic
Clastic
Non clastic
Weathering
Weathering
Chemical weatheing
Organic weathering
Mechanical weathering
Types of rocks
Sedimentary rocks
Metamorphic rocks
Igneous rocks
Kerogen types
Petroleum
Kerogen
Type I Kerogen
Type II Kerogen
Type III Kerogen
Type IV Kerogen
Structure Geology
Structure Geology
Structure Geology as the name indicates it is related to structures. What kind of structures are to be observed in this field?.The basic structures that is often used are
- Faults
- Folds
Faults
Faults are defined as the displacement or the movement in the rocks that make up the Earth's crust.![]() |
Figure 1. Fault in the Earth's crust. |
The block that moves relative to another is the hanging-wall and the block which is static at it's position is the foot wall. The foot wall can Move upward and downward. So the fault as divided are by this movement.
When hanging-wall moves downward with respect to action of gravity of the above burden it is called normal fault. And the hanging wall upward movement is called reverse fault as is against the gravity.
The major division of the faults are strike-slip and dip-slip
Strike slip faults are along strike so in order to understand the strike slip 1st strike should be known.
Strike is the line which is at right angle to the dip direction. Strike is formed by the intersection of dip direction and imaginary line that run along the horizontal surface.
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Figure 2. Strike and dip directions are shown. |
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Figure 3. On the lower left is reverse fault and to the right is strike slip or transform fault. |
Folds
Folds are the structures that are formed due to plate movements. Faults are also responsible in its forming. These are the folded starta of the Earth's crust the fold are formed when originally horizontal strata as deposition is always horizontal it is curved or bent, deformation in the strata due to forces.Figure 4. Component of fold. |
Anticline is shown in the figure 4 it is the convex upward fold. In it's inner part, lowest one will have the older rocks as it is the core and younger on the limbs and hinge. the syncline is the vice-versa. It will be concave upward and in the core the inner portion will have the younger rocks the limbs will have older rocks.