The document discusses paleomagnetism, the study of ancient magnetic fields in rocks, and its relevance to understanding geological history and climate change. It covers topics such as magnetization in various rock types, paleoclimatology methods like tree ring and pollen analysis, and the impacts of climate shifts during ice ages. Additional focus is given to the historical evidence of ice ages and their effects on sea levels and global climate patterns.

1. Palaeomegnetism,palaeoclimate,ice age’s
Name :- Darji Darshan. R
Geology paper no: 401
Roll No: 03
Supervision: Dr.m.v.majethiya
M. G. Science institute
(geology department)
Navrangpura, Ahmedabad, Gujarat 380009

2. Content
 What is palaeimegnetism
 Magnetization of minerals
 Magnetization In Sedimentary Rocks, Metamorphic Rocks
 Palaeoclimatology
 Type of palaeoclimetology
 Ice Age’S
 Past Ice Ages
 Reference

3. What is palaeomegnetism
 Paleomagnetism= ancient magnetic field.
 It is the study of magnetism in ancient rocks.
 Some rocks and materials contain minerals that respond to the
magnetic field.
 When rocks form, the minerals align with the magnetic field
preserving its position. It's called rock magnetism when rocks record
the position of the magnetic field.
 The magnetic signature of the rocks allows paleomagnetists to date
the rocks and map the position of the field at the time of their
formation.

4. Earth magnetism
WWW.ALAMY.COM WWW.WIKIPEDIA.COM

5. Magnetization of minerals
 Minerals can be magnetized and oriented with Earth's magnetic field
in a variety of ways.
 In molten rock, atoms of minerals are free to move and align
themselves with Earth’s magnetic field.
 When the rocks cool, attain form of igneous rocks the minerals are
then frozen in position and oriented along Earth's magnetic north-
south axis.
 Magnetic minerals found in rocks today, however, are not necessarily
oriented along Earth's present manetic north- south axis.

6. Continue...
 The deviation of a mineral's orientation to the present magnetic field
is of value in determining changes in Earth's structure in the past.
 Deviation may be inclined or declined.
 Declination is the angle between magnetic north (the direction the
north end of a compass needle points) and true north.
 Magnetic inclination is the angle made by a compass needle when the
compass is held in a vertical orientation.

7. Magnetization In Sedimentary Rocks, Metamorphic Rocks
 Sedimentary rocks Magnetic minerals can also be found in sedimentary
rocks. Sand, silt, clay, and other such materials are moved from place to
place by some agent, the magnetic minerals are constantly reoriented.
 When these materials finally settle out and form permanent accumulations,
they orient themselves with Earth's magnetic axis.
 These sediments, which may eventually become sedimentary rocks, can
preserve the orientation of Earth's magnetic field.
 Metamorphic Rocks Magnetization of minerals also occurs within
metamorphie rocks. Again, freedom of movement allows the minerals to
become magnetized along Earth's existing magnetic lines of force.

8. Palaeoclimatology
 Paleoclimatology is the study of past climates.
 Since it is not possible to go back in time to see what climates were
like, scientists use imprints created during past climate, known as
proxies, to interpret paleoclimate.
 Proxy data is data that paleoclimatologists gather from natural
recorders of climate variability, e.g., tree rings, ice cores, fossil
pollen, ocean sediments, coral and historical data.

10. Tree Ring Analysis
 Tree Ring Analysis Tree ring analysis is also
known dendrochronology.
 From the growth rings or tree rings we can
easily predict about the past climates.
 There are mainly two type of
chronologies.1. Anchored chronology 2.
Floating Chronology
 Also the instrument which used for the
taking cross section is called as Borer. WWW.WORLDHISTORYCOMMANS.COM

13. Pollen enalysis
 Pollen analysis is also known Palynology.
 Used for analyze the plant pollen
 Pollen grains rang size 10 to 150 um In
summer air is filled of pollens Palynologists
collects core of sediment or pea date layer
Pollen grains are well pressed in the
sediment layer in pond lake and oceans Type
of plants also identified pollen analysis to
study long-term patterns of vegetation
diversity.
 Prepared slide and add silicon oil, glycerol-
jelly and observed in scanning electron
microscopy. And they counts no. of grains of
each pollen taxon.
https://www.climate-encyclopedia.com/

14. Continue….
 Palaeoclimatological pollen records has become more quantitative and has
included more precise and rigorous testing of pollen-climate calibration
models with modern climate data.
 Pollen data provide of changes in vegetation , climate and human
disturbances of terrestrial ecosystem.
 Methodology :-
1.Palynomorphs
2.Chemical Preparation
3.Analysis

15. Isotopes
 The elements who have same atomic number but different atomic
weight those elements are called as Isotopes
 Oxygen is one of the most significant element for paleoclimatology
research.
 Oxygen is having three isotopes:160,170,180
 Occurrence of 160 and 180 in water changes and their ration in marine
sediments, ice or fossils is useful for studying cores paleoclimatology.
 On the basis of ocean water compression of oxygen isotopes at the
depth of 200-500 Evaporation and provides proxy data for the same.
 condensation of water Oxygen isotopes are generally naturally formed
isotopes.

16. Continue…..
• During ice age 016 is firstly
evaporated and then 018 which is
isotope so the existence of these
isotopes in glaciers or oceans provides
proxy data for the study
paleoclimatology.
• Oxygen isotopes preserving past
climate records.
https://pages.uoregon.edu/

17. Ice Malting And Sea level rise
 Sea ice influences climate because it reflects sunlight and because it
influences ocean circulation.
 Less sea ice leads to acceleration of global warming There is evidence
of ice melt, sea level rise to +5-9 m, and extreme storms in the prior
interglacial period that was less than 1°C warmer than today.
 Arctic sea-ice cover is shrinking by 8.9% per decade in summer and
2.5% per decade winter. It is also becoming thinner and there less
multi-year ice.
 Melting sea ice, in combination with melting glaciers and ice sheets,
may cause major changes to global patterns of ocean circulation.
 As with snow, less sea ice increases absorption of heat from the sun,
resulting in increased warming

18. Continue….

19. Ice Age’S
 INTRODUCTION An ice age is a period of long-term reduction in the
temperature of Earth's surface and atmosphere, resulting in the presence or
expansion of continental and polar ice alpine glaciers.
 Within a long-term ice age, individual pulses of cold climate are termed
"glacial periods" (or, alternatively, "glacials" or "glaciations", or colloquially
"ice ages"), and intermittent warm periods are called "interglacials".
 sheets and In the terminology of glaciology, ice age implies the presence of
extensive ice sheets in both northern and southern hemispheres.
 By this definition, we are in an interglacial period-the Holocene-of the ice
age.
 The ice age began 2.6 million years ago at the start of the Pleistocene epoch,
because the Greenland, Arctic, and Antarctic ice sheets still exist.
INTRODUCTION

20. Past Ice Age
http://iceage.museum.state.il.us/

21. The Late Cenozoic Ice Age
 The Ice Age we know best is the most recent. It appears to have begun with
the formation of an ice cap on Antarctica about 20 million years ago, or in the
early part of the Miocene time division of the Cenozoic Era.
 The evidence for this is the presence of rock fragments of this age found in
cores of sediment raised from the Southern Ocean.
 The only explanation for these fragments so far from land is their
transportation by icebergs that broke from a large, parent ice sheet on
Antarctica. Also layers of glacially deposited rock rubble are found in
Antarctica beneath lava flows whose age has been determined to be 10
million years by the process of radioactive dating of rocks.

22. THE PALEOZOIC ICE AGE
 Evidences of glaciation during at least some part of the Paleozoic Era are
found on all of the continents of the Southern Hemisphere. In Africa, for
example Gouges are found on rocks of Ordovician age in the Sahara Desert
(near the present equator).
 These Gouges are made by the erosional action of pebbles and rocks dragged
along the bottom of the glacier.
 Definite ice-deposited rocks of a somewhat later age are found all the way to
the southern tip of Africa.
 Despite the vastness of the areas covered by glacial ice in the Southern
Hemisphere, no glaciation of Paleozoic Age has been found anywhere in the
Northern Hemisphere except India.

23. REFERENCE
 WWW.WIKIPEDIA.COM
 https://pages.uoregon.edu/
 https://cdn.britannica.com/
 www.slideshare.com
 https://www.climate-encyclopedia.com/
 YOUTUBE :- NASA VIDEO’S