the geological history of earth

The geological history of the Earth Can be traced with the help of  Sedimentary rocks: composed of layers  Relative position of layers – information about the relative age  Fossils Scientists produced a geological With the help of these: timescale Geological timescale  Divided into units  Larger units = ERAS  Precambrian Represent major phases in the evolution of the planet  Palaeozoic  Mesozoic  Cainozoic divided into periods into epochs into ages The earliest events  The Earth is 4,6 billion 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 energy of collisions and nuclear fission generated heat Material became VERY HOT High temperature …  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 lost The Precambrian The longest era  Represents 87% of the geological history  Divided into parts Archeozoic Proterozoic Archeozoic  continuous decrease of temperature  water – liquid  plates of the lithosphere had been formed  volcanic activity:  result : The Composed of atmosphere first Permanent carbon dioxide, ammonia, steam The Himalayas North and South America  was connected at the end of the Tertiary  Ended the connection between the Atlantic and Pacific Oceans The most important localities of …  Brown coal  Oil and natural gas The Cainozoic Quaternary Period Began 2,4 million years ago  Distribution of continents and oceans was very similar to the present situation  Landscape was changed by the ice ages part: Pleistocene  Large areas were covered with ice sheets  The forming of large ice sheets needs: Cool summers rather than very cold winters, snow cannot melt during summer Snow can accumulate It becomes compacted to form large ice sheets Ice sheets covered large areas of North America and Europe Ice ages occur due to:  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 In the Pleistocene  Extension of ice sheets = glacials  Ice sheets became smaller = interglacials  The largest (47 million km²)  In Europe reached LONDON- COLOGNE-CRACOW- KIEV line  In North America: no mountains blocking the way of the ice: 40˚ Northern latitude Results  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) A large amount of water was captured in the ice sheets  The level of the sea sank significantly  Rivers changed their course When the ice began to melt…  Sea-level rose  Continents also started to rise after the weigh of the ice sheets disappeared The last ice age ended 10 000 years ago  The beginning of the Holocene  The present age is the beginning of an interglacial – a warmer period in an ice age? [...]...  Appeared later in the atmosphere  The result of: 1 UV radiation 2 Photosynthesis (after the appearance of plants) The temperature of the surface became cooler…  Under 100˚C Steam precipitated The first ocean was born Stromatolites  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... 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 (!) The Palaeozoic 1 Period: Cambrian  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. ..  East Greenland  Northern section of the Appalachian Mountains II Variscian: Carboniferous period  Connected Gondwanaland with the complex of Europe and N America  + Asian areas were added by  the Ural Mountains  South England  France  Mountains of Germany  The mountains surrounding the Bohemian Basin  Rhodope  Great Dividing Range in Australia  Southern section of the Appalachian Mountains... The plate of Australia and Antarctica   http://www.discoveringantarctica.org.uk/multimedia/flash/2_gondwana_fs.html Jurassic  The period of the reign of the dinosaurs Cretaceous  Fragmentation of Pangaea continued  Separation of South America and Africa  The basin of the Atlantic ocean became larger ... the sea: limestone and dolomite  For example: Transdanubian Uplands, Bükk Mountains Jurassic  Fragmentation of Pangaea began  Divided into 2 parts:  I Laurasia (North America, Europe, northern part of Asia)  II Gondwanaland  Tethys became an ocean The birth of the Atlantic ocean  Laurasia was divided into 2 parts Gondwanaland broke up into 3 large parts  South America  Africa  The plate of. .. section of the Appalachian Mountains  Velence Mountains By the end of the Palaeozoic  All continents had been connected  Huge continent = Pangaea  Surrounded by one huge ocean = Panthalassa  Huge bay in the eastern part of the continent: Tethys Carboniferous period  Main time when bituminous coal was formed  Tropical zone: huge forests The Mesozoic Divided into 3 periods: Triassic Jurassic Cretaceous... filter the radiation of the Sun Continents were NOT suitable for life (3.) Silurian period  Plants were the first to conquer continents (4.) Devonian period  The most significan changes: plants spread on land and the first animals appeared on continents 2 important orogenies  I Caledonian: Silurian period  Connected N America and Europe  Scandinavian Mountains  Mountains of Scotland Caledonides ... traced with the help of  Sedimentary rocks: composed of layers  Relative position of layers – information about the relative age  Fossils Scientists produced a geological With the help of these:... Mountains of Germany  The mountains surrounding the Bohemian Basin  Rhodope  Great Dividing Range in Australia  Southern section of the Appalachian Mountains  Velence Mountains By the end of the. .. 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