The Anthropocene is still considered an informal designation because International Union of Geological Sciences (IUGS)

The Anthropocene is still considered an informal designation because International Union of Geological Sciences (IUGS), the international organization that names and defines epochs, has not officially designated it an epoch.

Their criteria for the designation of a new epoch are that there should be evidence of human impacts and change in the rock record.

What activities and impact could humans be responsible for that might be reflected in the rock record and thus determine the beginning of the Anthropocene?
(Minimum of two sentences )