[Petrochemicals (OP)]

It is often said water wears away stone, but does it really, in water jet cutting water is not actually much good at cutting hard materials unless an abrasive is added, garnet Ruby and saphire being common. So can an H20 drip really abrade stone.

[evan_au]

Water can dissolve some components of stone (eg limestone), releasing the less soluble parts to be carried downstream.
- Moving water can carry sediment, which abrades the rock
- Water can get into cracks and freeze; expanding ice breaks off bit of rock.
- Salty water can get into rocks and evaporate; the salt crystals break the rock grains
- Frozen water (ie glaciers) can break off rocks, which then abrade other rocks.
- Ocean waves carry a lot of momentum, which breaks and erodes rocks

[paul cotter]

Evan_au has covered many points concerning erosion but I have one addition. Many substances are referred to as being soluble or insoluble in water but this is a simplification as those considered insoluble have a finite but very small solubility. Everything will dissolve in water to some extent even if the solubility is infinitesimal and over time some loss can be expected.

[alancalverd]

Rainwater is slightly acidic as it contains dissolved CO2.

[vhfpmr]

https://www.youtube.com/shorts/YrEgZoC2vo8
https://www.youtube.com/shorts/DMYazT57QIc

[paul cotter]

And that co2 partly converts calcium carbonate in the limestone to the slightly more soluble calcium bicarbonate, Ca(HCo3)2

[Petrochemicals (OP)]

Water can dissolve some components of stone (eg limestone), releasing the less soluble parts to be carried downstream.
- Moving water can carry sediment, which abrades the rock
- Water can get into cracks and freeze; expanding ice breaks off bit of rock.
- Salty water can get into rocks and evaporate; the salt crystals break the rock grains
- Frozen water (ie glaciers) can break off rocks, which then abrade other rocks.
- Ocean waves carry a lot of momentum, which breaks and erodes rocks

Thank you Evan. I am looking for how water itself rather than any other substances like salts wears away hard. Also as an interesting fact, a few years ago I learned than the freeze thaw action that everyone is taught actually is mostly to do with liquid water being subjected to pressure because of the ice expansion, basically high pressure fracturing.

[paul cotter]

Water is rarely present in pure form and in terms of geology there is almost always particulates and dissolved substances present.

[Petrochemicals (OP)]

Water is rarely present in pure form and in terms of geology there is almost always particulates and dissolved substances present.

Does this mean that water does in fact fail to damage hard rock, but is merely a conveyance device?

[paul cotter]

Petro, I am neither a chemist nor a geologist but my guess is that pure static water would have very little or no effect on hard rock.

[Bored chemist]

The reason why you seldom see pure water in nature is because... it has rock dissolved in it.
It also dissolves CO2 from the air.