Not too sure what kind of rock this is, very interesting looking. Anyone have an ideas. Was found north of the badlands, South of Rapid City.
closed as off-topic by Universal_learner, arkaia, Fred, trond hansen, Jan Doggen Jul 12 at 9:33
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "Please review our rock identification guidelines to provide the missing information so that your question is both answerable and useful to new users." – Universal_learner, arkaia, Fred, trond hansen, Jan Doggen
You have a rock called conglomerate. This rock is basically a bunch of other rock fragments that were transported in some kind of stream or river, became rounded, and then got buried under other layers of sediment. This burial caused the individual pieces of rock to stick together to form one hard rock.
A quick look at a geological map of South Dakota shows that the area you described has limestone, sandstone, shale, and other similar sedimentary rocks. Looking at your picture - this seems very reasonable. I have a strong feeling that the white pieces are limestone, the yellow pieces are sandstone, and they grey stuff is some kind of hardened clay that cements everything together. To confirm this, do the following:
- Scratch it with a knife. The yellow sandstone will resist scratching. The grey clay and white limestone will not.
- Put some white vinegar on it. The white will fizz, the clay might fizz and the sandstone will not fizz or fizz just a tiny little bit.