I have you beat by a couple of years http://www.lustria-online.com/threads/just-for-laughs.16182/page-3#post-137631 Way back from page 3 of this thread... old school!
You will admit that with 475 pages, I can be excused... That was because I was looking for some funny geologist memes...
The thing on the picture looks like a "volcanic plug", which is basically what is left from a really really old volcano that got eroded by wind and rain. Based on what we know about the materials it consists of, and how the movement of the tectonic plates can be measured, we can tell how old it is. We can use that information to debunk weird stories about the Earth's age, like for example the ones told by creationists who claim the Earth is 6000 years old. (I had some geology at university so I had a good laugh there)
Just a quick terminology note, not all creationists believe the earth is 6000 years old. Those are generally known Young Earth Creationists (or YEC). The other two primary positions are Old Earth Creationists (OEC) and Theistic Evolutionist and they would be highly insulted that you conflate them with YECs. Now back to your regularly scheduled entertaining memes.