Mechanical weathering -- tree roots

Mechanically weathered clasts on a mountain side

exfoliation

Heat-cold weathered clast in the desert

Controls on chemical weathering

Rock type

(name of the rock)

granite Basalt (higher T minerals)

Rainfall Low rainfall High rainfall (H2O, O2, combination with CO2)

Temperature Cooler temps Higher temps (heat speeds up reactions)

Vegetation Sparse vegetation = lower rate (nothing to promote chem rxns)

Lots of vegetation – plants create oxygen, tannins, acids

Soil cover More soil cover/rocks exposed at surface

OR More soil cover: Soil decomposes, gives off heat, holds rain water, chm rxn

SLOW FAST

A few questions about seawater

• What are the main ions in seawater (what makes it salty)?

• Where do these ions come from (where do most ions in seawater come from)?

• Why is seawater so salty?

Poorly sorted conglomerate

Coarse-grained sandstone

Very fine-grained sandstone/siltstone

chert

limestone

travertine

Angular clasts in a very fine matrix (poorly sorted, close to source)

Round clasts, well sorted, diverse types, far from source

Beds (lake beds actually)

The text’s wordon how to creategraded bedding