Which undefined term is used to define an angle?

Which statements are accurate about snow flakes

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.

Acharreadas is a popular mexican thing where people display varying skills of horsemanship much like what events in the united states?