What I Learnt In Class -Photo Geology And How It Helps In The Interpretation Of Geologic Features On The Ground.

Fellow eSteemed!!

It's been a week since I posted. I have been very busy lately, preparing for school and getting acquainted with the school environment once again. We have been on holidays for the past six months and it's as if I just got admitted again. Staying at home for a very long duration like that, can make you forget you were a student.

But right now I'm back with a lot of interesting topics from the geologic world. I once stated in my introductory post that I was an undergraduate studying geology and also shared some pictures.

Studying Geology is really exciting because you get to go on field trips and interact with those things you have learnt in class. Everything becomes real to you as you can relate what you have learnt in class to what you will see in reality. Let me get back to the main purpose of this post.

I will be talking about what I learnt today in class. It was really interesting, so I decided to share it with everyone. I learnt about Photo Geology and how it helps in the interpretation of geologic features on the ground.
Firstly,

What is Photo Geology

According to merriam-webster dictionary

Photo Geology is a branch of geology concerned with the identification and study of geological features through the study of aerial or orbital photographs.

Source

Image Source

It is more about the interpretation of geology, geomorphogical features as well as various facies and by doing this, aerial photographs are used because they are pictures used to source geological information on ground surface taken from the air with a camera pointing downwards. They can't be substituted for field investigation but as a contribution towards a successful field investigation.

The aerial photographs are taken by an airborne vehicle(drone, helicopter, satellites and balloons) with camera attached to it.
Stereoscope is the instrument used in interpretation of aerial photographs and there are two types of Stereoscope

1. Pocket/lens Stereoscope
2. Mirror Stereoscope

Image Source
Pocket Stereoscope The pocket Stereoscope is mostly used because it's smaller and can be easily transported from one location to another.

Image Source
Mirror Stereoscope

Most of these photographs are black and white recorded largely by variation in Tone and Relief.

Relief

Every object has a unique relief and it's the relative resistance of rock to erosion. For example a dyke intruding different rock units. A relief can be positive or negative. A negative relief is observed when the rocks are easily erodable and positive when the rock is resistance to weathering.

Tones

Tone is the quality of photograph in terms of darkness and brightness. Black been the strongest and white the weakest. Every object has a distinct tone. It is so because it can be affected by the nature of the rock, the light conditions, characteristics of the film, influence of filter or effect of processing. The most important features are :

• Reflection of light comes with the ability to absorb i.e the more the light absorbs the darker the tone.
• The tone of intrusion is related to its intrusion. The more the basic intrusion, the darker the tone is
• Among bedded rocks, such as sandstone, limestone ,chalk and schist they tend to photograph in a light tone. Some intermediate rock such as andesite does too.

Photographic appearances of rock is affected by the following factors

• Climate
• Sun cover
• Vegetation cover
• Erosion
• Colour
• Texture
• Relative erosion to surrounding rocks
• Physical characteristics
• Composition of the rock
• Lineament : Any line on the aerial photograph that is structural controlled.

Advantages of Photo Geology

• It saves more time than actual name field mapping.
• Observes a large area more detailed than a map.
• It can be studied anywhere and anytime. Since they are photographs they can be carried around and studied at your leisure.
• It is cheap.

Disadvantages of Photo Geology

• No contour and geological name
• More training is required to interpret it.
  According my lecturer you need a relaxed and excited mind to be able to study an aerial photograph.

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Reference

Definition of Photogeology

My Class Note Book