2. Concepts of the plate tectonics
Milestones
continents were connected once
Alfred Wegener (1912) ‘Continental Drift’
Arthur Holmes (1930) convectional currents
Hess & Dietz (1960) sea floor spreading
The history of Earth’s crust’ conference (1966,
New York)
4. Evidences of the hypothesis
► Geographic fit of
South America and
Africa
► Fossils match across the
ocean
► Climatology
► Rock types and structures
match across oceans
5. Evidences of the hypothesis
► Geographic fit of South
America and Africa
► Fossils match across
the ocean
► Climatology
► Rock types and structures
match across oceans
6. Evidences of the hypothesis
► Geographic fit of South
America and Africa
► Fossils match across the
ocean
► Climatology
► Rock types and structures
match across oceans
7. Evidences of the hypothesis
► Geographic fit of South
America and Africa
► Fossils match across the
ocean
► Climatology
► Rock types and
structures match
across oceans
Good afternoon everyone, it’s a pleasure to welcome you today. Let me just start by introducing myself. For those of you who don’t now me, my name is Laszlo Bertalan and I am a first year PhD-student at Department of Physical Geography and Geoinformatics. The subject of my presentation is about movement of continents and according to that theory the developing landforms. In my presentation I’ll focus on three major issues. I’ll begin with the evolution of the theory of plate tectonics then I’ll move on to its geological background and finally I’ll describe the concrete processes about landform development in the related areas. It will take about 20minutes to cover these issues.
So, let me first give you a brief overview about the theory of plate tectonics was born. First, way back in the 17th century, scientists with wide knowledge suggested the idea that the continents were once connected to each other. However, the concept of Continental Drift was first published and introduced into geology by an Austrian meteorologist, Alfred Wegener in 1912. The next step was when in 1930 Arthur Holmes suggested that convectional currents in the Earth’s mantle causes the drifting of oceanic crust. Later, two American geologists, namely Hess and Dietz proposed the idea of sea floor spreading and took the third and final step towards global plate tectonic concept. Finally the concept of plate tectonics was accepted by scientific public at a conference in New York in 1966.
Wegener thought that all the continents were once joined together in one large supercontinent , named Pangea. Later this landmass split up and the continents drifted apart to the recent locations as we know them nowadays.
Now let’s see the solid but simple evidences of plate tectonics. If you see the map of the world, you may notice that some of the continents could fit together like pieces of a puzzle…..the shape of Africa and South America are a good example. This is because they DID used to fit together! The Earth as we see it today was not always like it is now. Land masses have pulled apart and joined together by the process called Plate Tectonics. As well as we can see it on the example of fossils. Same types of fossils and same aged fossils (for example Mesosaurus) can be found through over the lands of ancient supercontinent used to fit together. These animals obviously were not able to sail across the ocean. Ancient glaciation indicated that parts of southern Africa, India, Australia, and South America were covered by a large ice cap . The sharp-edged boundar ies on both sides of the shores of the Atlantic Ocean can suggest that they used to be in one part .
Now let’s see the solid but simple evidences of plate tectonics. If you see the map of the world, you may notice that some of the continents could fit together like pieces of a puzzle…..the shape of Africa and South America are a good example. This is because they DID used to fit together! The Earth as we see it today was not always like it is now. Land masses have pulled apart and joined together by the process called Plate Tectonics. As well as we can see it on the example of fossils. Same types of fossils and same aged fossils (for example Mesosaurus) can be found through over the lands of ancient supercontinent used to fit together. These animals obviously were not able to sail across the ocean. Ancient glaciation indicated that parts of southern Africa, India, Australia, and South America were covered by a large ice cap . The sharp-edged boundar ies on both sides of the shores of the Atlantic Ocean can suggest that they used to be in one part .
Now let’s see the solid but simple evidences of plate tectonics. If you see the map of the world, you may notice that some of the continents could fit together like pieces of a puzzle…..the shape of Africa and South America are a good example. This is because they DID used to fit together! The Earth as we see it today was not always like it is now. Land masses have pulled apart and joined together by the process called Plate Tectonics. As well as we can see it on the example of fossils. Same types of fossils and same aged fossils (for example Mesosaurus) can be found through over the lands of ancient supercontinent used to fit together. These animals obviously were not able to sail across the ocean. Ancient glaciation indicated that parts of southern Africa, India, Australia, and South America were covered by a large ice cap . The sharp-edged boundar ies on both sides of the shores of the Atlantic Ocean can suggest that they used to be in one part .
Now let’s see the solid but simple evidences of plate tectonics. If you see the map of the world, you may notice that some of the continents could fit together like pieces of a puzzle…..the shape of Africa and South America are a good example. This is because they DID used to fit together! The Earth as we see it today was not always like it is now. Land masses have pulled apart and joined together by the process called Plate Tectonics. As well as we can see it on the example of fossils. Same types of fossils and same aged fossils (for example Mesosaurus) can be found through over the lands of ancient supercontinent used to fit together. These animals obviously were not able to sail across the ocean. Ancient glaciation indicated that parts of southern Africa, India, Australia, and South America were covered by a large ice cap . The sharp-edged boundar ies on both sides of the shores of the Atlantic Ocean can suggest that they used to be in one part .
In this part of my presentation I’d like to talk about the interior of the Earth. It is divided into layers based on chemical and physical properties. The Earth has an outer silica-rich, solid crust, a highly viscous mantle, and a core comprising a liquid outer core that is much less viscous than the mantle, and a solid inner core.
In the mantle under great pressure the hot material is circulating and this phenomena is known as conventional currents. As a result of convection currents, plates start to drift apart . This leads directly to my next point…
Let’s now look at the next slide which shows that the lithosphere is devided into 7 major and several smaller lithospheric plates and then these plates are in constant motion relative to each other. Let’s look under these plates…
In three different situations we can find the plate boundaries. Plate boundaries can be div, conv, trans boundaries. I would like to briefly summarize their main characteristics. The former one is also called spreading centers , where two plates just simply move apart . The material silently erupting forms the youngest part of the oceanic crust. The next one occurs where two plates move together , as a result the thinner oceanic crust is forced to sink under the continental crust. The latest one can be observed where two plates grind past each other without the production or destruction of the lithosphere .
