# Are these igneous rocks? **URL:** \ **Category:** Factual Questions\ **Created:** [July 27, 2005, 7:33am UTC](https://boards.straightdope.com/t/are-these-igneous-rocks/314376 "2005-07-27T07:33:48Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Thin\_Lizzy](https://avatars.discourse-cdn.com/v4/letter/t/e9a140/32.png) [@Thin\_Lizzy](https://boards.straightdope.com/u/Thin_Lizzy)\ **Post date:** [July 27, 2005, 7:33am UTC](https://boards.straightdope.com/t/are-these-igneous-rocks/314376/1 "2005-07-27T07:33:48Z")
I had to dig a 3 foot hole in the yard for a drywell, and would come upon rocks of various. sizes and started wondering, how is it that the rocks wound up scattered under the surface instead of one big mass. are these igneous rocks? ---
**Author:** ![ouryL](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ouryl/32/6067_2.png) [@ouryL](https://boards.straightdope.com/u/ouryL)\ **Post date:** [July 27, 2005, 7:39am UTC](https://boards.straightdope.com/t/are-these-igneous-rocks/314376/2 "2005-07-27T07:39:31Z")
Rock can also degrade due to weathering, so it’s hard to say. Maybe someone dumped it there as fill? 😕 ---
**Author:** ![Thin\_Lizzy](https://avatars.discourse-cdn.com/v4/letter/t/e9a140/32.png) [@Thin\_Lizzy](https://boards.straightdope.com/u/Thin_Lizzy)\ **Post date:** [July 27, 2005, 7:46am UTC](https://boards.straightdope.com/t/are-these-igneous-rocks/314376/3 "2005-07-27T07:46:14Z")
> [@ouryL](#): > > Rock can also degrade due to weathering, so it’s hard to say. Maybe someone dumped it there as fill? 😕 oh no it was nothing like that, I just mean the occasional rocks you find when you dig ---
**Author:** ![antechinus](https://avatars.discourse-cdn.com/v4/letter/a/fbc32d/32.png) [@antechinus](https://boards.straightdope.com/u/antechinus)\ **Post date:** [July 27, 2005, 10:51am UTC](https://boards.straightdope.com/t/are-these-igneous-rocks/314376/4 "2005-07-27T10:51:27Z")
Over the hundreds of thousands of years, rock formed from volcanic ejecta breaks down into smaller pieces as it is weathered through various processes, chemical and physical. This also works to form the soil in which these rocks are found. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [July 27, 2005, 11:24am UTC](https://boards.straightdope.com/t/are-these-igneous-rocks/314376/5 "2005-07-27T11:24:54Z")
> [@Thin Lizzy](#): > > I had to dig a 3 foot hole in the yard for a drywell, and would come upon rocks of various. sizes and started wondering, how is it that the rocks wound up scattered under the surface instead of one big mass. are these igneous rocks? They could be almost any kind of rocks; they can pretty much all get broken up into pieces by a variety of natural processes. ---
**Author:** ![Hanna](https://avatars.discourse-cdn.com/v4/letter/h/b3f665/32.png) [@Hanna](https://boards.straightdope.com/u/Hanna)\ **Post date:** [July 27, 2005, 1:13pm UTC](https://boards.straightdope.com/t/are-these-igneous-rocks/314376/6 "2005-07-27T13:13:04Z")
Could be glacial till; glaciers are notoriously bad at sorting rocks by sizes (like other methods of transport will do). As pointed out, they could be other types of rocks, not just igneous. ---
**Author:** ![butler1850](https://avatars.discourse-cdn.com/v4/letter/b/779978/32.png) [@butler1850](https://boards.straightdope.com/u/butler1850)\ **Post date:** [July 27, 2005, 2:00pm UTC](https://boards.straightdope.com/t/are-these-igneous-rocks/314376/7 "2005-07-27T14:00:54Z")
The first question is where is the OP? That could immediately rule out, or positively identify the rocks, perhaps just by the location. ---
**Author:** ![Thin\_Lizzy](https://avatars.discourse-cdn.com/v4/letter/t/e9a140/32.png) [@Thin\_Lizzy](https://boards.straightdope.com/u/Thin_Lizzy)\ **Post date:** [July 28, 2005, 1:13am UTC](https://boards.straightdope.com/t/are-these-igneous-rocks/314376/8 "2005-07-28T01:13:02Z")
[QUOTE=butler1850] The first question is where is the OP? That could immediately rule out, or positively identify the rocks, perhaps just by the location.[ In North Carolina ---
**Author:** ![butler1850](https://avatars.discourse-cdn.com/v4/letter/b/779978/32.png) [@butler1850](https://boards.straightdope.com/u/butler1850)\ **Post date:** [July 28, 2005, 3:02pm UTC](https://boards.straightdope.com/t/are-these-igneous-rocks/314376/9 "2005-07-28T15:02:10Z")
[This](http://gw.ehnr.state.nc.us/faq.htm) site might help. About 1/2 way down, it breaks out NC into areas, and describes the geology of those areas. If you’re in an area that was a true igneous area, that might answer your question. Or if a friendly geologist dropped in, they might be able to tell you more. As your a guest, some friendly info: The more information you can provide, description of the rock and your location (a bit more detailed than the state level) would have helped earlier in the thread. We’ve a huge diversity of expertiese here, and it’s a shame not to get an answer due to insufficient information. I’m not a geologist, but the question interested me enough to look around. good luck! -Butler