Question

Sandstones that form in aeolian (wind/desert) environments appear very different from other sandstones, such as those formed in a beach/shoreline environment and in rivers on land. Give three identifying properties for each of the three sandstones that would tell a geologist which depositional environment they formed in. Consider things such as the relationship between transportation and grain size, shape, roundness, sorting, fossils and composition

Answer 1

Answer:

Three identifying properties that would help tell a geologist which depositional environment a sandstone was formed in is sorting, roundness, and composition. Sandstone that has formed in an Aeolian environment will have well sorted particles that are rounded. Sandstone that has formed in a beach/shoreline environment will also be very well sorted. Sandstone formed in rivers on land will be poorly sorted. The longer amount of time particles are transported the better sorted they will form. Rounded grains are more likely to have been transported by water or wind for a longer time such as in a sedimentary rock formed in an Aeolian environment by wind or one formed in a beach/shoreline environment by waves. Sandstone formed in an Aeolian environment will have a larger quantity of quartz as it is a more durable mineral than feldspar and ferromagnesian. Sandstone that has a significant amount of feldspar and ferromagnesium minerals is more likely to have gone through little chemical weathering and transport and was probably deposited close to the source area of the rock particles. We can also tell a lot by the kind of fossils that are fossilized in a sedimentary rock by analyzing what kind of organism or plant it is and if they were found on land or in water during that time period.

Answer 2

Answer:

The three discerning properties include sorting, roundness and the composition of the sandstone.

Explanation:

Sandstone that has been created in an Aeolian environment will have well formed particles that are rounded.

Sandstone that has been formed in a beach/shoreline environment will also be very well sorted.

Sandstone formed in rivers on land will be poorly sorted as the waves will have the effect on them.

Sandstone formed in an Aeolian environment will have a greater quantity of quartz as it is a more withstanding material to the aeolian shear.

Sandstone that has a significant amount of feldspar and ferromagnesian minerals clearly indicate the lower level of chemical weathering which is not a case in the aeolian environments.