Seminar on“Palaeomap and climate of different ages and reconstruction of the past

climates”Presented by:PULOKETO .K ACHUMI3rd SEMESTER MSc. GEOLOGYDOS IN EARTH SCIENCEUNIVERSITY OF MYSOREGUIDED BY:PROF.M.S.SETHUMHADAVPROFESSOR, DOS IN EARTH SCIENCEUNIVRSITY OF MYSORE date : 7th oct. 2011

CONTENTS

• INTRODUCTION• MAPS OF DIFFERENT AGES AND

THEIR CLIMATES• MAJOR ICE AGES• RECONSTRUCTION OF THE

PAST CLIMATES

•CONCLUSION

INTRODUCTION• Climate : the sum of all statistical weather

informations of a particular area during a specific interval of time.

• Palaeoclimatology : the study of changes in climate through out geological time.

• The climate of the earth has varied on all timescales.

• Paleomaps are map of continents and their position at different ages.

• With reference to the position of the continents as one of the factors, the climate of the past changed at different ages

MAPS OF DIFFERENT AGES AND THEIR CLIMATES

PRECAMBRIAN• Hadean : harsh terresterial

environment, low oxygen(1%), high CO2(10%).

• Archean : no free oxygen, reducing condition, composed of methane, CO2 and H. like the present day Venus and Jupiter

• Proterozoic : oxygen rich i.e from reducing to oxygenated. Warm conditions replaced by an Ice Age, might have covered the whole earth

PALAEOZOIC ERACambrian Period

•Gondwanaland; Located near the south pole, covered by glaciers •North America, Europe, Siberia and Asia were all separate. •Warm and arid in early part.•Atmospheric oxygen attains the present levels, generating an ozone shield.•Evidence of arid climate: cambrian of the salt range- salt pseudomorphs

Ordovician Period

•Collision of the continents.

•North America and Europe were coming together .

•Earth suffered the coldest time, large extinction caused by the glaciations of gondwana.•Irregularity in temperature i.e. fluctuation of warm and cold intervals

Silurian Period

•North America and Europe joined by the end of the Silurian.

•The Siberian/Asian continent was converging on Europe.

•The North America/Europe continent began to approach Gondwanaland.

•Generally warm and possible dry climate.•Aridity evident by halite pseudomorphs and salt spring in the Baltic,Russia

Devonian Period

•Continued approach of North America towards Gondwanaland.

•N. America, Europe, Asia and Siberia were beginning to form a second supercontinent: Laurasia.

•Arid climate, aridity suggested by an abundance of red beds, evaporites.

Carboniferous Period

•Gondwanaland collided with North America forming the southern Appalachian Mountains.

•warm and humid during the early period•Massive ice age, covering gondwanaland.•Glaciers alternated with coal swamps, developed a glossopteris flora indicative of a cool climate.

Permian Period

•Asia collides with Europe to form the Ural Mountains.

•One large supercontinent (called Pangea) forms with the merging of Laurasia and Gondwanaland.

•mass extinction possibly due to ocean cooling or fluctuating due to ice sheet., reduced aquatic environments due to Pangaea forming, ash from large volcanic eruptions in Siberia.

Mesozoic eraTriassic period

• All landmass concentrated into one-Pangaea, surrounded by oceans -Panthalassa

• The Triassic climate was generally hot and dry, forming typical red bed sandstones and evaporites.

Jurassic Period

•Pangea began to break up with the rifting of North America, drifting to the northwest.

•Atlantic Ocean began to open.

•Sea level began to rise and global temperatures continued to become warmer and wetter.

Cretaceous Period

•Small land masses on the subducting Pacific Plate collided with North America.

•Warm climate, mean global temperature may have been 6 to 8 degrees higher then today.

Cenozoic Era

•North & South America, Australia and Antarctica spread away from Pangea, further opening the Atlantic Ocean. •Africa collided with

Europe; India collided with Asia.

•The early Cenozoic was another period of mountain building in the Rocky Mountains.

Cenozoic climate

• Palaeogene was warm and tropical.• Neogene saw a drastic cooling• Continued cooling in Pleistocene

resulted in new ice age• Late Cenozoic climate fluctuated

repeatedly between cold and warm

• Over all this time there were other changes taking place:

.

Variation in O2 levels in the atmosphere

Variation in carbon dioxide

Variation in global temperature.

Major ice ages

Reconstruction of the past climate

• Drilling ice cores : studying the entrapped fossil air, measuring the amount of CO2, methane and other greenhouse gases to study the warming of the atmosphere.

• Palaeosol:deep red paleosols were much more common

during the warm climates and suggest wetter, Paleosols from colder time periods tend to be brown or green in color.

• Plant fossil study : smooth margined leaf

species indicate a warm climate and vice versa.

• Dendroclimatology : tree rings are broad in years of favourable conditions and narrow otherwise.

• Sclerochronology: coral records

study, dark bands are a result of low temperature during winter and light bands are produced when growth rate is faster when the temperature is high.

conclusion

• The climate of the earth has varied on all timescale.

• Climate change is a dynamic phenomenon, and has been changing ever since its existence.

• Oxygen shifted from reducing to oxygenated conditions.

• The change in climate is attributed to : movement of the continents, change in the composition of atmosphere, volcanic eruptions, changes in the earth-sun geometry and changes in the solar output etc.

References 1. Schwarzbach; Climates of the past,1963 : published by D.Van Nostrand

Company Ltd.Pp.19-70 2. D.S.Lal; Climatology,Revised edition 2010,published by Sharda Pustak

Bhavan Publishers & Distributors, Allahabad,Pp.379-391 3. Ronald Pearson; Climate and Evolution, published by Academic Press

Inc.111 Fifth Avenue,New York, Pp.115-177 4. H.H.Lamb;Climate:Present,past and future,volume-2 published by

Methuen & Co Ltd.New York Pp.280-308 5. L.A.Frakes ; Climate throughout geologic time, published by Elsevier

Scientific Publishing Company,Netherlands Pp.57-185 6. U.B.Mathur; Climate change:Past present and future, published by

Geological Society of India, Bangalore Pp.5-25

7. INTERNET SOURCE : http://www.wikipedia.com http://www.palaeomapproject/us.in

Thank you