Erosion vs weathering - different processes that work together

Waterfalls and plunge pool - evidence of erosion and weathering

I used to be confused by the two terms - weathering and erosion.  The reason, I suppose, is that they are often mentioned together; you don't typically have one without the other.  And, although related, they couldn't be more different.

Weathering is the process by which material is broken down.  This usually involves rock, but could also refer to soil or chemicals that break down or dissolve.  The forces of weathering are water, wind, changes in temperature and pressure, chemistry, and anything else that causes material to break away from a mass.

Erosion either follows or is concurrent with weathering.  Erosion is simply the movement of material.  The forces of erosion are water, wind, gravity, and anything else that physically causes stuff to move.  

The entire surface of the Earth has been shaped because of weathering and erosion.  Glaciers, waves, mass movement, cave formation, and flowing water are examples of the natural processes that shape the continents and ocean bottom.  

There are multiple aspects of weathering and erosion in the photo above.  Rain falls on the land.  The water making up the rain dissolves carbon dioxide and other chemicals, making it slightly acidic.  This evokes chemical weathering.  The physical act of water falling from the sky causes particles to move and continues through surface motion; materials dissolve in the water on land and particles are moved by the action of water.  The water eventually makes it to a stream, where material is carried along with it; rocks are rounded because of chemical and physical processes.  More material follows.  The water comes to a precipice where it falls into a plunge pool.  The hydrodynamic forces of water falling carve out the pool and cause the edge of the waterfall to move slowly backwards.  Material is broken down and moved, eventually where it finds itself producing a sedimentary layer somewhere.  

This is where the rock cycle kicks in, which is another physical and chemical process altogether.  Then, it happens all over again.  

Isn't that amazing?

Thanks for reading.

Eric Svendsen     www.ericspix.com