If our impact on the environment continues on its current trajectory, then geologists in the distant future on Earth probably won't be human. But they will be able to detect a boundary in the geological record between the current Holocene Period and what some are now calling the Anthropocene Period. The Anthropocene Period is the time when humans began to have a significant impact on the environment.

Source:
http://www.npr.org/blogs/13.7/2011/06/21/137317694/the-anthropocene-can-humans-survive-a-human-age


I learned about this at http://andrewsullivan.thedailybeast.com/2011/06/a-man-made-earth.html