Why Does This Happen Or How Does This Happen?

Question

If a rock cliff face or any other stone breaks away from its main attachment (Hope you understand this) it has a jagged edges.

So why do the majority of stones you find have smooth edges?

Thanks

Answer 1

Rocks that break and fall will have the jagged edges becase usually they crack from weathering or some kind of force and break away along that crack....this creates the hard shard and rough edges.....the stones you find all over the place that are smooth have been weathered and eroded into the shapes you see....after a while that same rock that broke away will become smooth through the process of erosion....

its like when your looking at a conglomerate rock, if those rocks that are cemented together have been eroded and aree smooth its known as a conglomerate whereas if they are rough and have been worn down then they are breccias....

Answer 2

The first fall of the rocks starts the smoothing process (sharp protruding edges are knocked off in the initial fall

Then the wind /frost and rain take hold causing abrasion and eventually all jagged edges are smoothed away

Imagine a car in a wind tunnel the more streamlined it is the better the flow of air over it ,so once the jagged edges are gone erosion slows down (But does not stop !!) eventually a boulder becomes a stone and then sand or earth etc depending on it's initial composition

Answer 3

Actually, it is not the process of erosion that smooths the jagged edges.  Erosion is the transport of weathered material.

The process of weathering is what makes the jagged edges smooth.

Weathering can be physical or chemical.

Some scientist include a separate type of weathering which is termed biological weathering.  An example of this is root pry.

Physical weathering breaks down the rock into smaller pieces that have the same chemical composition as the parent rock.

Chemical weathering actually changes the chemical composition.

Types of mechanical weathering include:

abrasion by wind or water, ice wedging, root pry.

Types of chemical weathering include:

hydrolysis, oxidation and carbonation.

Answer 4

When the rock first breaks and falls it will have sharp edges and corners because it is broken.  However when those sharp edges are exposed to the effects of water, wind and air they immediately begin to weather.  Weathering happens on the surface, and corners have proportionally more surface than rounded edges so corners will weather fastest, leading to the rounded look.  There need not be any abrasion involved, simply the action of water and oxygen on the rock surface (The minerals will be hydrated and oxygenated).  The degree of weathering will depend ont he type of rock - igneous rocks will round more quickly than sandstones for example.

However, if the rock is transported downslope in a stream then abrasion will also assist rounding.