the geological history of earth

 Began 2,5 billion years ago Several orogenies – produced the oldest parts of the crust = the so-called shields  Shields form the core of continents  They were originally mountain r

The geological history of the Earth

 Sedimentary rocks: composed of layers

 Relative position of layers – information about the relative age

 Fossils

With the help of these:

Can be traced with the help of

Scientists produced a geological

timescale

 Divided into units

 Larger units = ERAS

 The Earth is years old

 Formed from a huge cloud of gas and dust

 Meteorites played an important role in the early life, added to its mass

The earliest events

4,6 billion

The energy of collisions and nuclear

fission generated heat

Material became VERY

HOT

 Led to the chemical differentiation

of the material into different layers

 Iron and nickel sank into the centre

 Less dense materials formed

concentric layers around the core

 The young Earth had an atmosphere – it was lostHigh temperature …

The Precambrian

 Represents 87% of the geological history

 Divided into 2 parts

2. Proterozoic

The longest era

 continuous decrease of temperature

 Appeared later in the atmosphere

 The result of:

1. UV radiation

2. Photosynthesis

(after the appearance of plants)

Oxygen

 Under 100˚C

The temperature of the surface became cooler…

Steam precipitated

The first ocean

was born

 Provide the first geological evidence of life

 Rocks with special spherical structure

 Blue algae play an important role in their formation

 The oldest 2,9 billion years old

(Being formed in

present day Australia)

Stromatolites

 Began 2,5 billion years ago

 Several orogenies – produced

the oldest parts of the crust = the so-called shields

 Shields form the core of continents

 They were originally mountain ranges which were eroded later

 Later orogenies did not change them (!)

2 Proterozoic

The Palaeozoic

 The first fossils – animals with hard parts (Skeletal material)

 Living beings could only be found in seas and oceans

 The atmosphere did NOT filter the radiation of the Sun

1 Period: Cambrian

Continents were NOT

suitable for life

 Plants were the first to conquer continents

(3.) Silurian period

 The most significan changes: plants spread on land and the first animals appeared on continents

(4.) Devonian period

 I Caledonian: Silurian period

 Connected Gondwanaland with the complex of Europe and N America

 + Asian areas were added by

 the Ural Mountains

 Great Dividing Range in Australia

 Southern section of the Appalachian Mountains

 Velence Mountains

II Variscian: Carboniferous period

 All continents had been connected

 Huge continent = Pangaea

 Surrounded by one huge ocean = Panthalassa

 Huge bay in the eastern part of the continent: Tethys

By the end of the Palaeozoic

 Main time when bituminous coal was formed

 Tropical zone: huge forests

Carboniferous period

Divided into 3 periods:

Triassic Jurassic Cretaceous

The Mesozoic

 Calm period: sedimentation

 Areas flooded by the sea: limestone and dolomite

 For example: Transdanubian Uplands, Bükk

Mountains

Triassic

 Fragmentation of Pangaea began

 Divided into 2 parts:

 I Laurasia (North America, Europe, northern part of Asia)

Jurassic

 Laurasia was divided into 2 parts

The birth of the Atlantic ocean

 The period of the reign of the dinosaurs

Jurassic

 Fragmentation of Pangaea continued

 Separation of South America and Africa

 The basin of the Atlantic ocean became larger

Cretaceous

 Continued in the Cainozoic

 African plate drifted closer to the Eurasian plate:

Tethys bacame smaller and smaller

Alpine – Himalayan orogeny began

 Collision of oceanic and continental plates

The forming of mountain ranges around the Pacific Ocean began

Tertiary Period

Quaternary Period

The Cainozoic

 The orogenies - began in the Mesozoic – continued

 The mountains around the Pacific Ocean rose

 Kuril Islands

 The mountains of Japan

 Cordilleras in North America

Tertiary Period

The Andes

The Cordilleras

 North America from Europe was completed

 Australia and Antarctica began

Separation of …

 was destroyed

 The 2 continental plates of Eurasia and Africa collided

 The Mediterranean Sea and the Black Sea are the only remaining parts

The basin of the Tethys …

 was built up of sediments of the Tethys

 and material of the African and Eurasian plates

 Most important mountain ranges:

 The Atlas Mountains – Africa

 The Pyrenees

 The Alps

 The Appennines

 The Carpathians

 The Dinaric Alps

 The Balkan Mountains

 The Caucasian Mountains

The Alpine system

 The mountains of Northwest Asia

 The mountains around the Iranian Plateau

 The Himalayas

 The indo-Australian Plate collided with the Eurasian Plate in the 2nd half of the Tertiary

The Himalayas

 was connected at the end of the Tertiary

 Ended the connection between the Atlantic and Pacific Oceans

North and South America

 Brown coal

 Oil and natural gas

The most important localities of …

Quaternary Period

The Cainozoic

 Distribution of continents and oceans was very similar

to the present situation

 Landscape was changed by the ice ages

Began 2,4 million years ago

 Large areas were covered with ice sheets

 The forming of large ice sheets needs:

1. Cool summers rather than very cold winters, snow

cannot melt during summer

3. It becomes compacted to form large ice sheets

1 part: Pleistocene

Ice sheets covered large areas of North America and Europe

 Astronomical factors:

The course of the revolution of the Earth changes over long periods of time

 Changes in the energy production of the Sun as well

Ice ages occur due to:

 Extension of ice sheets = glacials

COLOGNE-CRACOW-KIEV line

ice: 40˚ Northern latitude

In the Pleistocene

 Lakes of Finland: erosion of the ice

 North European Plain: lots of sediments were deposited

 Climate and vegetation were changed

 (in the Sahara the climate was more humid, in Hungary similar to the present-day climate of Lappland)

Results

 The level of the sea sank significantly

 Rivers changed their course

A large amount of water was captured in the ice sheets

 The beginning of the Holocene

 The present age is the beginning of an interglacial – a warmer period in an ice age?

The last ice age ended 10 000 years ago