Posted: Mar 02, 2010 1:13 am
The_Piper wrote:Thanks guys. Speculate away Theropod, I'm learning new stuffAs long as you don't mind.
I've been busy trying to find out the age of the rocks around here. I finally found this map http://www.maine.gov/doc/nrimc/mgs/explore/bedrock/facts/geol-hist-1.htm and I'm certain that I lie either in the area of middle Ordovician to middle Devonian, or Cambrian to middle Ordovician. That map has no reference points, and I am near the border of the 2 zones.
Also, this region was affected by glaciers. There is vertical strata along the same brook...by strata I mean the layers of sediment in boulders, etc, that are visible in lines
The rock seems like a ball of igneous rock with sedimentary rocks stuck to the outside. I know little more than that for terminology unfortunately. The igneous rock looks and feels like granite, but it "glistens" more, is darker, and looks like it might be more dense. The "teeth" also look like granite, of a lighter, more familiar color than in between the teeth. They also "glisten". It's appears to be 4 different small rocks stuck to the outside. It's a little dirty from brook sediment. I turned it over on it's side and a small piece of the corner flaked off from the darker colored sedimentary rock. It revealed a reddish stain on the interior. I see that a lot with sedimentary rocks found in the area. There is a dark flaky sedimentary rock on both flat sides, and also a gray colored rock on both sides that is more solid. I think it is sedimentary also because I found another rock in the brook with definite fossils in this type of rock. It looks somewhat like compressed beach sand.
I might have some luck finding someone in the area with at least a little working knowledge, but no one I can think of yet. Population here, 247
I took many more pictures, but my camera is pretty lousy at close-ups.
Here is the other fossil I found, about 10-15 yards downstream, and 3 years prior.
Top
http://xs.to/image-4721_4B729C91.jpg
Bottom
http://xs.to/image-F459_4B729C91.jpg
Edit: Edited on behalf of the Op - Mazille
Piper,
Well, I'm sorry but I don't think these are fossils in the sense that most folks think of them. I think the first object with the "teeth" is where intrusions of some sort have penetrated fissures and resulted in silicate crystals forming in these bands. These fissures may have resulted from exposed mud drying and cracking and then being covered with mud of a different texture and composition. Again, without some crisp close-ups I'm speculating wildly.
Is the layers sandwiching the the "teeth" layer both the same type of rock?
Try this on the non-tooth layers. As a test you could try a 3 part water one part white vinegar etching. If you can form a masking "dike" with warm wax, and then allow to cool, so that only a small portion of the surface can be exposed to the acid you can find out if the stone is of a limestone composition. If the rock is limestone it will react with a fizz. When the fizzing stops clean off the wax damn/dike, wash the area with a baking soda water (1 part soda 5 parts water by volume acid neutralizer), allow to dry, and examine the etched area with as high power magnifier as you can. Report what you see, and the reaction to the acid solution. This weak solution should only clean the area and not erode the rock to any great extent. If the rock is non reactive we need to take another tack.
The second object looks to me like limestone that has been etched by ground water that has absorbed tannin from decomposing hardwood leaves. This is a natural etching process much like the procedure above. This same type of stone can often be found near areas where caves can be found.
Keep me informed and we'll get to the bottom of this.
RS