Every so often coastline naturally erodes and land falls into the ocean. How do we still have land?
In: Planetary Science
Volcanic and tectonic activity. The plates are still moving, and the ones pushing into each other sometimes create uplift, raising mountains ever so gradually. Also volcanoes shoot molten rock directly onto the surface, either creating new islands in the ocean or piling the land that much higher. Granted it’s not measurably one-for-one with erosion but I just mean to say there are some forces adding to the land rather than taking away from it.
Land is also constantly being pushed UP from under the ocean. Volcanic actively will spew out lava that then solidifies into a new piece of land. And tectonic activity will have two or more plates smash into each other and push some land up.
Interestingly enough you are definitely on to something. “older” land tends to be less mountainous and closer to see level precisely because of erosion.
Underneath both the water and the rock on the surface, there’s a whole load more rock – thick plates of solid rock floating on a layer of molten rock – and that rock is moving (albeit very slowly most of the time)
Sometimes two bits/plates of rock run into each other, and one of them buckles, pushing upwards and becoming a mountain range. That mountain range will take a long time to erode down until it’s back at ground level, and in the mean time more mountain ranges will form elsewhere.
Sometimes two bits of rock move apart, and the space in between allows the molten rock from even lower down to flow upwards, creating a volcano. As with mountain ranges, volcanoes take a long time to erode down to nothing, and in the mean time more volcanoes will keep forming.
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