Um... neeeed details plz!
Answer:
To survive. Drinking is very important and is required for animals and organisms to survive. It also keeps us hydrated.
Bloodstain pattern analysts sometimes are called to gruesome scenes to gather crucial evidence regarding violent crimes. At other times, they might deal only with a single drop of blood or fingerprint.
Erosion is brought about by the forces of nature or human activity: water, wind, earthquakes, mining, quarrying, etc. In the desert, there is very little water that can cause weathering or erosion, so the most probable answer is wind or maybe even animal activity.
