Detail description on the folds and faults of the rock structure.

1. Fault

2. 2
Forces that cause deformation
Ductile
Brittle
Convergent Divergent Transform

3. • Fracturing is favoured when the stresses are
shearing in nature and the rocks are brittle in
character.
• Fractures along which there has been relative
movement of the blocks past each other are
termed as faults.
• The entire process of development of
fractures and displacement of the blocks
against each other is termed as faulting.

4. – Footwall (rock mass
below the fault)
Hanging wall
(rock mass
above the fault)
Fault blocks classified as

5. • Dip-slip faults – Motion is parallel to fault dip.
• Strike-slip faults – Motion is parallel to fault
strike.
Fault Types

6. • Two dominant types
– Normal fault
– Reverse Fault
• Thrust (a low angle reverse fault)
Types of Dip-Slip Faults

7. NORMAL FAULT
- a fault along which the hanging wall has moved relatively
downward
- caused by tensional stress-stress that acts to pull the crust
apart.
- causes overall extension of the crust.

8. REVERSE FAULT
A Reverse Faults: is a thrust fault that dips
more than 45 .
Reverse faulting is a response to compression.
Reverse faulting shortens the horizontal extent
of the crust.

9. • Strike-slip fault
• Transform fault
– Large strike-slip fault that cuts through the
lithosphere
– Accommodates motion between two large crustal
plates
Strike-Slip Faults

10. NORMAL FAULT

11. Hanging
wall
Foot
wall

12. THRUST FAULT-COMPRESSIONAL

13. ATTITUDE OF FAULTS
The Strike of fault is the trend of a horizontal
line in the plane of the fault.
The Dip is the angle between a horizontal
surface and the plane of the fault; It is
measured in a vertical plane that strikes at right
angles to the fault.

14. Joints
In geology the term joint refers to a fracture in rock
where the displacement associated with the
opening of the fracture is greater than the
displacement due to lateral movement in the plane
of the fracture (up, down or sideways) of one side
relative to the other

15. Columnar joints

16. Exfoliation joints

17. Columnar joints

20. GEOPHYSICAL METHODS
GEOLOGICAL SITE INVESTIGATIONS
•Artificially introduced FORCES INTO GEOLOGIC
FORMATIONS.
•Used in assessing
•Ground conditions
•Materials
•Groundwater

21. ELECTRICAL RESISTIVITY METHODS
•ELECTRICAL SOUNDING – WENNER (1915)
•PRINCIPLE: based on the principle that
electrical resistivity of loose unconsolidated or
partially consolidated surface materials like the
products of rock weathering and erosion such as
soil loess, alluvium, sand and clay is different
from that of bedrock over which they are
deposited.
•Electrical resistivity – shows difference
•Loose unconsolidated or partially consolidated
surface materials (rock weathering and erosion)
•Lower electrical resistance –in more porous or
jointed and fissured the rock.
•Igneous and metamorphic rock in general –
greater resistance than the sedimentary rocks.

23. In resistivity soundings,
the distance between the current electrodes
or the distance between the current and potential dipoles is
expanded in a regular manner between readings,
thus yielding information of the electrical properties of soils from
deeper and deeper depths.
Electrode arrangement

24. In resistivity profiling, the electrode spacing is fixed, and
measurements are taken at successive intervals along a profile.
Data are generally presented as profiles or contour maps and
interpreted qualitatively.

25. •EQUIPMENTS
•A generator or a high voltage battery (200 v) – source of current
•A measuring assembly
•A voltmeter
•A potentiometer - for measuring small potential differences
accurately
•A multi-range milli-ammeter – for measuring currents
•Four stainless steel, copper, or other metallic spikes (electrodes).
• 800 m long and 20 mm diameter
•heads for easy driving into ground
•clamps for cable connection
•stranded insulated single conductor cable
•0.5 m conducting area
•cable parable needs
•devices for eliminating effects of polarization of electrode and
small currents in the ground
•spares.

26. P=resistivity in ohm
V=potential difference
i=current in amperes d=1/3 ,a,, where a =total
distance between outer electrodes

28. SEISMIC METHODS
•PRINCIPLE
•Seismic (elastic) waves travel through subsurface
materials (soil and rock) at difference velocities.
•Their propagation – influenced by certain
combinations of density, modulus of elasticity and
poisson;s ratio of geologic bodies.
•Suffer – absorption, reflection and refraction -
comparable to optical phenomena.
Measuring the time taken by the seismic waves set
up by an explosion at the surface to travel directly or
after suffering reflection and refraction at subsurface
discontinuities and determine the depth of bedrock

30. •REFRACTION METHOD
•Determining the distance between the Earth’s surface and one or
more reflecting surface i.e. depth to bedrock (HRL) and or
thickness underground on the basis of the travel – time of seismic
waves.
•EQUIPMENT :- shallow refraction seismic equipments.
•Geophones (seismometer) three to twelve vibration detectors
•A battery operated amplifier unit with several independent
amplifiers for each geophone detector.
•A multichannel oscillograph
•An exploder
•Charge ( dynamite)
•Insulated cable
•A portable processing facilities
•Spares.

31. •FIELD PROCEDURE AND
INTERPRETATION
•A hole – shot hole – 1.5 – 2mts kg –
dynamite
•Geophones – straight line – profile –
shooting
•Round shot hole – arc-shooting / fan –
shooting
•SEISMIC SPREAD – the area over which
the exploration is made from a given shot
point is called seismic spread.
•Plotting the first arrival times and
distances i.e. the time elapsed between the
explosion and reception of the waves by
variations.
•Travel distance graph – hodograph
•D = x/2 v2-v1 / v2 = v1 where v1 =
velocity of seismic waves in overburden
•V2 = velocity of seismic waves in bed
rock
•X = critical distance
•D = depth to bedrock.

32. •FIELD PROCEDURE AND
INTERPRETATION
•A hole – shot hole – 1.5 – 2mts kg –
dynamite
•Geophones – straight line – profile –
shooting
•Round shot hole – arc-shooting / fan –
shooting
•SEISMIC SPREAD – the area over which
the exploration is made from a given shot
point is called seismic spread.
•Plotting the first arrival times and
distances i.e. the time elapsed between the
explosion and reception of the waves by
variations.
•Travel distance graph – hodograph
•D = x/2 v2-v1 / v2 = v1 where v1 =
velocity of seismic waves in overburden
•V2 = velocity of seismic waves in bed
rock
•X = critical distance
•D = depth to bedrock.

33. •FIELD PROCEDURE AND INTERPRETATION
•A hole – shot hole – 1.5 – 2mts kg – dynamite
•Geophones – straight line – profile – shooting
•Round shot hole – arc-shooting / fan –
shooting
•SEISMIC SPREAD – the area over which the
exploration is made from a given shot point is
called seismic spread.
•Plotting the first arrival times and distances i.e.
the time elapsed between the explosion and
reception of the waves by variations.
•Travel distance graph – hodograph
•D = x/2 v2-v1 / v2 = v1 where v1 = velocity of
seismic waves in overburden
•V2 = velocity of seismic waves in bed rock
•X = critical distance
•D = depth to bedrock.