The waves are one of the agents that manage to cause large scale erosion and deposition. The influence of the waves in the erosive and deposition processes are along the coastlines. The composition of the waves is simply water, of course the water has certain other chemicals in it, but very importantly it has a lot of power pushing it forward. The combination of the chemical composition and the power results in the waves to be able to cause both chemical and mechanical weathering along the coastlines. By doing so, they manage to break the rocks in smaller pieces, and then easily move the material away, thus cause erosion. The material, depending on its size and weight, can be moved only few meters right next to the beach, further into the water but still close to the coastline, or on the beach itself. As the material is transported and then left off at certain places, we have deposition, which in turn causes constant pilling up of new material, so over time new and interesting features are forming from the deposited material.
The lithospheric plates float over the viscous layer of the asthenosphere due to the initiation of convection current in the mantle. These currents are formed because of the heat that is radiated from the core of the earth.
In a divergent plate boundary, the two plates move away from one another. Due to this, seafloor spreading takes place and leads to the eruption of magma forming a ridge which is commonly known as the Mid-Oceanic ridge. Here, new materials are added to the crust.
When the continental plates are stretched and pulled apart due to the extensional force, it results in the formation of a rift, and gradually with time, it forms a rift valley. This rift valley later give rise to the formation of seas and oceans due to the tectonic activities.
The oceanic crust is made up of denser basaltic rocks containing a high amount of magnesium, calcium, iron, and aluminum, whereas the continental crust is comprised of less dense granitic rocks containing silicate minerals, feldspar. So the oceanic crust is denser than the continental crust.
The thickness of the continental and oceanic crust is about 35-45 km and 5 to 10 km respectively. Hence, the continental crust is very thick.
The hotspots are the regions that are comprised of mantle plumes, where the magma is so intense that it rises up to the surface forming volcanoes or volcanic landforms.
The ice floating over water is similar to that of the moving of the crusts over the mantle. The thickness and density, both play a significant role in keeping the crust at the top of mantle maintaining the state of equilibrium. This is known as isostasy.
1. Coal is in the underground and we have to dig it out. Water is always there and circulating. Wind and Solar are things that have and will exist for a long time. We can use them and cycle them
