2.
Any definable shape/fabric in a rock body.
It is a large scale feature.
easily noticed.
Divided into :-
1)Primary structures
2)secondary structures
What is a structure?
3.
Structures that are developed during formation of
rock, or shortly after formation.
Non tectonic forces (exo genetic forces are
responsible)
Mainly show the direction of flow of the forming
agent.( wind, water, ice etc )
Primary structures
5.
According to law of uniformitarianism, sediments will
accumulate horizontally while getting deposited.
Bedding is a planar arrangement of particles which can be
easily distinguished by difference in color, composition and
texture.
≥ 1cm in thickness.
Lamination is a term used if particles arrange themselves
same as bedding but their thickness is less than 1 cm.
Bedding and lamination
6.
7.
It is formed on tilted surface during deposition by
crossing a bed to another one.
It is in between topmost bed and fore set bed.
Indicates the direction of the paleocurrents.
Cross bedding
8.
9. It is bedding in which the particles are sorted
according to density, size and shape.
Particles in water settle at different rates depending
on size, density and shape. forming "graded bed"
with layers of coarse material deposited first and
finer grains deposited later.
Normal and reverse grading are the types.
Graded bedding
10.
11.
Are wavy undulating features formed by wind, wave
or current.
Indicate the ancient and modern sedimentary
environment.
Formed in shallow waters.
Also show the direction of flow.(Asymmetric ripples)
Divided into :- symmetric and asymmetric.
Ancient ripple marks preserved as casts.
Ripple marks
12.
13.
Mud cracks are often found in the fine grained
sedimentary rocks that has been exposed to drying
under subaerial conditions.
They form a network of fissures enclosing polygonal
areas.
Indicate once present water body.
Ancient mudcracks preserved as casts.
Mudcracks
14.
15.
A rain print is a slight shallow depression rimmed by
a low ridge which is raised by the impact of rain
drops.
It is formed when a brief rain shower falls on a
smooth fine grained sediment.
Rain prints
16.
Trails and tracks are the markings indicating the
passage of some animals over the soft sediment.
Trails and tracks
17.
Are variously shaped masses or nodules of mineral
matter found within a sedimentary rock.
They are formed by the deposition of the perlocating
mineral solution.
Concretions
18. Major breaks in sedimentation is called unconformity
Simply put any observable difference indicating the
gap in sedimentation.
hiatus
4 types:-
Angular unconformity
Disconformity
Non conformity
paraunconformity
Unconformity
21.
Dyke (dike) is discordant, or cross cutting, tabular
intrusion, usually igneous in origin, Vertical or nearly
vertical, having pushed the country rock way and
generally harder than them.
Dykes
22.
Sills also called sheet, flat intrusion of igneous rock
that forms between preexisting layers of rock
generally concordant with the bedding planes of the
surrounding rocks.
Sill
23. A batholith is a large mass of intrusive igneous rock,
larger than 100 square kilometres in area, that forms
from cooled magma deep in the Earth's crust.
Batholiths are almost always made mostly of felsic or
intermediate rock types, such as granite..
Batholith
24.
A laccolith is a lens shaped(mushroom shaped)
intrusive igneous body which causes the overlying
bed to arch in the shape of a dome.
laccolith
25.
A lopolith is a saucer shaped(bowl shaped) igneous
body which is bent in downward into a basin like
shape.
lopolith
26.
Phacoliths are the crescent shaped igneous bodies,
they occupy the crests and troughs of igneous strata.
Phacoliths are formed whenigneous material invaded
the folded strata.
Phacolith
27.
Pillow lavas are lavas that contain characteristic
pillow-shaped structures that are attributed to the
extrusion of the lava under water, or subaqueous
extrusion. Pillow lavas are commonly of basaltic
composition.
Pillow lava
28. Ropy or pahoehoe lava is a lava marked with smooth
wrinkles resembling rope.
Blocky or Aa lava has solid chunks formed due to rapid
flow and rapid cooling.
Ropy and blocky lava
29.
Volcanic products form these
Volcanic breccia: >4mm and angular clasts.
Agglomerate: rounded fragments >4mm
Tuff : <4mm
Ash flows or ignimbrite: Very very fine.
Pyroclastic flows
30.
31.
Columnar jointing is a geological structure where
sets of intersecting closely spaced fractures, referred
to as joints, result in the formation of a regular array
of polygonal prisms, or columns.
These form when igneous material comes out from
restricted zones and cools down.
Columnar joints
32. Gas cavities which are formed due to escaping of
volatiles in a igneous rock manifests vesicular
structure.
When these vesicles get filled with secondary
minerals ,it forms Amygdaloidal structure.
Vesicular and Amygdaloidal
33.
structures which are formed after the formation of
rocks.
Mainly Tectonic forces (Endogenetic forces) are
responsible.
Folds, faults, joints, lineations.
Obviously I wont explain, our friends will explain this
secondary structures.
Secondary structures
34.
Eat well
Do regular exercise
Invest time in studies
Strict hand washing is compulsory.
Follow the precautions issued by government.
As we are living through a historic moment ourselves lets
stand united and stay home.
#STAY HOME STAY SAFE#
Hope everyone is taking care of
themselves
