12. 3- Why do landscapes change?
CHANGES IN RELIEF
EROSION: the wearing away of rocks and other
deposits on the earth's surface by the action of water,
ice, wind, etc.
SEDIMENTATION: material that has been deposited
from water, ice, or wind.
17. 4- How does relief shape our planet?
Continental drift theory
Continental drift is the movement of the Earth's continents relative to
each other by appearing to drift across the ocean bed. The concept
was developed by Alfred Wegener in 1912. The theory of continental
drift was supported by the theory of plate tectonics, which explains
how the continents move.
Evidence for the movement of continents on tectonic plates is now
extensive. Similar plant and animal fossils are found around different
continent shores, suggesting that they were once joined.
Pangaea (/pænˈdʒiːə/) was a supercontinent that existed during the late
Paleozoic and early Mesozoic eras, forming about 300 million years
ago. It began to break apart around 200 million years ago. The single
global ocean which surrounded Pangaea is accordingly named
Panthalassa.
20. Tectonic plates
A theory that explains the global distribution of geological phenomena
such as seismicity, volcanism, continental drift, and mountain
building in terms of the formation, destruction, movement, and
interaction of the earth's lithospheric plates.