Creek cuts or road cuts are often an open history book not of recent times but of times long gone. Perhaps millions of years can be read in one spot. This is knowledge I hunger for and spend endless time trying to "read" the geological happenings that created this place, this time.
Above is a creek cut with layers of clay alternating with layers of lime. This could be read as a long time of drought followed by a body of water which caused the lime build up. The time of water was long because of the sediment and the fact water with lime began seeping into the clay or silt stone. Both are considering sedimentary rocks.
Then, Boom! There's a nice shelf of igneous rock bubbling out of the creek floor. Now this is where it gets confusing to me. This could be metamorphic rock because "
Metamorphism is the result of solidification of material under high temperature and pressure. There are two types of metamorphism, contact and regional. The difference between the two is simple. Contact will occur in a small area usually as a result of an igneous intrusion. Regional occur in a large area due to intense heat and pressure within the earth." So could it be an igneous intrusion cooling as it is reaching the surface which then makes it a metamorphic stone? Metamorphic stone is made by squashing or heating.
Are you confused yet? I am.
At this point I know I don't know enough unless all I need to know about rocks is the pleasure of collecting and just listening to what they have to say.
I know barely enough to know if it's sedimentary, igneous or metamorphic...sometimes but I surely have fun trying to figure it out because under these main divisions are many, many more.
...and that is your geology lesson for the day.
Knowing there is no simple stone keeps me looking.
