§ 10. Geological history
1. Remember what geological time.
2. What does geochronological table?
Geologic time. As you already know from previous geography course, forming the earth's crust began more than 4 billion years ago. Crust and its surface (relief) for the while continuously changed and continue to evolve under the influence of internal and external forces of the Earth. The composition, structure, origin and development of the crust studies geology, and changes in Earth's crust over time known geological history of Earth.
As you know, time is divided into geological era: Archean, Proterozoic, Paleozoic, Mesozoic, Cenozoic. In erah, except the oldest, distinguish periods. Archean and Proterozoic era often called PrecambrianIe time which preceded the Cambrian Paleozoic era. It is in the Precambrian formed the foundation of modern lifestyles on Earth: There was the first stone crust and were the original form of organic life.
Geochronological table for the territory of Ukraine
Geological History of Ukraine. The table below presents geochronological table, which displays the geological history of Ukraine. In it the main intervals of geological time (eramy and periods) shows the development of the earth's crust and relief, changing environmental conditions (climate, vegetation and wildlife) on in our country. For consistent play events geochronological table reads from the bottom up - from end to beginning.
В Archean era continental Earth crust within the country consisted of crystalline rocks of magmatic and metamorphic origin. She was very thin and plastic. As a result of internal forces Planet Earth's crust has been subjected to various movements: vertical and horizontal, smooth and discontinuous. In some places it in the curved fold forming folded mountain structures in others - rozlamuvalasya into separate blocks. Along fault occurs magmatism. Sometimes the hot magma propikala thin earth crust and flooded a large area on its surface. At the end of era separate large parts of the earth's crust lose plasticity and become a thick stverdili area. Thus began the formation of ancient East Platform, within which lies most of the territory of Ukraine. Earth's atmosphere at that time was intense various gases, but without oxygen. Condensation skupchuvalasya at high altitude, only Earth's surface cooled it began to fall precipitation. In watersheds with'Appeared to bacteria and algae.
У Proterozoic era internal forces of the Earth broke crystal platform based on blocks various sizes. Some of them remained on the surface or prypidnyalysya, they breed constantly wracked and worn under the influence of external forces. Other units sunk down upon them accumulated sedimentary deposits. Most active this occurred in marine basins that he attacked on land, then retreated from it depending on the direction vertical movement the crust. Unlike platform crust in the south and southwest Ukraine remained unstable and plastic. This is part Mediterranean mobile beltplanet, which prolih south through contemporary Eurasia. There, during the whole geological history of Earth's crust then fell, then rose. When retracting repeatedly appeared flexural deformations of the earth's surface faults. Buckling zatoplyuvalysya sea and they accumulated sediment thickness powerful. When the deflection experienced elevation formed folded mountains (orogenesis age or folding). In the crack breaks from the depths penetrated magma, forming separate volcanic ranges or target ranges.
У Paleozoic era Central part in Ukraine was mostly dry. In other territories continental and marine conditions changed each other. Maximum sea attack as a result of lowering the earth's crust took place in the middle age. In the Paleozoic occurred two horoutvoryuyuchi era, which influenced the formation of crust Ukraine. In Caledonian folding mountain facilities have in place modern Carpathians - PrakarpatyThat the islands were from the water. In hertsynsku folding (Late era), they disappeared under the waters shallow Sea Tethys, deflection that took in Mediterranean moving belt. Instead, the new folded structureappeared in the east of the site Donetsk deflection. The climate was close to the subtropical: mostly hot, varied from dry to wet. Early in the era of single-celled organisms evolved. Then there were multicellular algae, marine invertebrates and vertebrates animals, and another milyonolittya - Terrestrial plants and amphibians. In coal-term dominated lush vegetation: giant moss, horsetail, tree ferns, which contributed to a substantial Thickness of coal.
У Mesozoic era On the platform part of Ukraine prevailed flat land. Private pools of water existed on Left Bank and in the Mediterranean zone. However, in Cretaceous Period was the largest for the entire geological History of Ukraine distribution of marine areas. They covered almost the entire territory our country, except the central part. In Mesozoic revealed Kovalenko NA Cimmerian folding, because of which formed the mountain structure in place in Crimea, Azov Sea and the North part of the Black Sea. But then the mountain collapsed and became the sea floor. In Transcarpathia were active volcanoes. The climate was mostly warm and dry. Conifers and angiosperms developed, such as plants. There mammals and birds.
Early Cainozoic eraSeaway again spread to most of the territory of Ukraine. Over time sea gradually receded. As a result Alpine orogeny era Carpathian and finally formed Crimean mountain building. In Quaternary (antropohenovomu)period was raised almost the entire territory of Ukraine except Black. The climate was mostly warm and moderately humid. Vegetation and fauna gradually acquired modern traits appeared human. In Antropogene was a general cooling and drying climate, which led to several glacial epochs in Europe. Most - Dnipro icing - spread to much of the territory of Ukraine. After the melting of glaciers formed a modern look natural environment - terrain, rivers, soil, vegetation and fauna.
Fig. The southern border of the Dnieper glaciation in Ukraine
Fig. Distribution of land and sea in different geological periods
For hundreds of millions of years Precambrian crust in the territory of Ukraine was formed only under the influence internal forces of the Earth, as a result of high temperature on the Earth's surface hydrosphere existed, it splattering rain, there was constant circulation atmosphere. The surface crust resembling lunar landscape with high raising and volcanoes, and del breaks, large "Craters" formed in the fall of meteorites.
Under pressure from the glacier
Vertical movements of the earth's crust can occur not only as a result of internal forces of the Earth, but external. Thus, the pressure enormous mass of glaciers crust Ukraine fell, while the postglacial era, like a sigh of relief, she stood up. Despite lowering the earth's crust, the Black Sea has come not to South of Ukraine. On the contrary, its level was more than 100 m lower than now. This is because while icing it loose connection with the Mediterranean and has not received inflows of river water frozen land.
Geochronological table shows the development of the Earth crust and changing environmental conditions by major geological time intervals (eramy, periods).
Crust on the territory of Ukraine was formed almost 4 billion years from the Precambrian period. As a result of internal forces of planet Earth's crust has been subjected to various movements: vertical and horizontal, smooth and discontinuous.
Crust formation occurred during horoutvoryuyuchyh epochs (folding) – Caledonian, hertsynskoyi, Mesozoic (Cimmerian), Alpine.
У Quaternary Cainozoic era was a general cooling of climate, which led to the Dnieper glaciation.
Questions and Tasks
1. Using geochronological table set: a) that the ancient era, b) that era still in progress and in) the era in which most distinguished periods, d) in that era was Alpine horotvorennya.
2. According to geochronological table describe history of the earth's crust: a) East-European platform; b) moving in the Mediterranean zone.
3. As in Ukraine have changed the natural conditions during the Dnieper glaciation?