Concretion and nodules are two geological formations that are with a host strata.
Indian marbles, iron concretions, are red spots in the Aztec Sandstone, subsurface water has caused iron oxide around a nucleus in the sandstone. These concretions are more resistant to erosion than the surrounding sadstone, and weather into little balls known as Indian or Moqui Marbles.
Concretions are often ovoid or spherical in shape, irregular shapes also occor. The word "concretion" comes from the Latin con meaning 'together' and crescere meaning 'to grow'. The concretions form within the layers of sedimentary strata that have already been deposited. They usually form early in the burial history of the sediment, before the sediment hardens into rock. This often makes the concretion harder and more resistant to weathering.
Concretions vary in shape hardness and size. some requiring a magnifying lens to huge bodies weighing several thousand pounds.
Nodules are small irregularl rounded knot, mass, or lump of a mineral or mineral aggregate that typically has a contrasting compositon. Ex: pyrite nodule in coal, chert nodule in limestone, or phosporite nodule in marine shale. Nodule normally have a warty of knobby surface and exists as a descrete mass withing the host strata.
To qualify for this cache email me the answers to the following questions:
1. The title: "Nature Lost Her Marbles" and the GC code "GC5NJJR"
2. How many people are in your group? Please provide the name of the geocachers.
3. In this area do you find concretions or nodules.
4. What is the texture of them in this area?
5. Name two types of concretions.
Pictures optional, but don't post any with the actual geological feature. I would enjoy have them added to the log.
The above information was compiled from:
http://www.redrockcanyonlv.org/redrockcanyon/geology-highlights/
http://en.wikipedia.org/wiki/Concretion
http://en.wikipedia.org/wiki/Nodule_(geology)
http://en.wikipedia.org/wiki/Nodule_(geology)