Accretionary Wedge #57 - Seeing Geology Everywhere
Evelyn at Georneys has put out a call for post here
accretionary-wedge-57-seeing-geology-everywhere/
I
like to walk. No; that's not right - I love to walk. If I don't do any
other form of exercise for the day I always try to get a walk in. Most
of the time I like to walk a set course that is a little less than 3
miles. I follow the sidewalks in my neighborhood. And as I walk I
like to meditate on things or just think about things in general. Most
of the time I brood about my family and the things that are going on
within it. But other times I like to clear my mind and just think about
things in general. One of my favorite general things to think about is
geology. I love it because I see it everywhere. And as I walk I can
see all sorts of geological things going on in the sidewalks that I walk
on.
So now Evelyn has put out this call and as I was
walking I was trying to figure what I was going to write about. I was
getting thirsty on this walk. Ta -da - something popped into my head - I
know I can write about Slurpees and how when you suck on the straw too
fast you break the capillary action and don't get anything out of it,
but if you suck on it really slowly and steadily you can get so much
more out of it. I used to use this explanation all the time in
discussing how to produce an oil field. For awhile I was a
developmental geologist and it was my job to help design how a
discovered oil field could be produced to obtain its maximum
production. Most of the time when I would start talking about why
drawing the oil out too fast wasn't good for the field, I would hit
resistance - they wanted get as much out as fast as they could. But if I
got a slurpee and had them see how it draws down they could understand
that.
So that was what I was thinking about as I was walking.
And the more I was walking the more I was thinking about getting that
slurpee when I was done. Boy would it be good, especially since the
weather was already in the nineties.
But then gosh darn it wouldn't you know I would see something and the geology just popped out at me. This is what I saw:
Here
Evelyn wanted cat stuff and in the side walk was these cat paw
impressions, and also these molds being infilled with sandy material.
All
I could think about were those paleontology courses and how rare it is
to get a land animal imprints and what would someone a million years
from now think about this stuff if they discovered it while doing an
excavation of the area.
It also got me thinking about how when
I see wet concrete there is just something in me that wants to leave an
imprint. These people had the same impulse that I had and put their
imprints for the rest of us to see for a long, long time. It also got
me thing about years ago we did some remodeling and had to pour some
concrete and we did something very similar. When I got home I checked
to see if I could still find it and I could get to a part of it but the
rest was covered over.
So
I continued to walk and thought about the geology I was seeing. And
trying to decide what I should be writing about. Then I came upon this
weathered stain.
It
reminded me so much of a field trip I was on where I saw something
similar. If I recalled these red spots were from iron oxide weathering
out from siderite.
Decisions,
decisions- the more I thought about it I should just stick with the
sidewalk stuff and see what I could come up with.
It wasn't long before I came upon stuff like this to make up my mind.
When
you first look at this you think oh- more iron oxide staining but then
when I looked closer I realized there had been an magnolia petal that
had deteriorated there. This stain wouldn't last long but the other
will stay for a long time.
Then there were other things like this which finally made up my mind for me and made me want to do sidewalk geology instead.
Here
was a vug where at one time there had been some organic matter that had
gotten into the cement and had deteriorated leaving this hole. Now its
being filled in with other debris.
I
wondered if this hole had been created the same way? But when I looked
at it more I decided it may have been an air pocket that collapsed when
the cement hardened or else there could have been a pebble that was
slightly higher and had popped out.
Then
I saw this crack that really showed the cement cracking out of it and
creating holes that way. It's so interesting to see how the cement
cracks and weathers.
Look
at this radial cracking. It looked like something may have impacted
this sidewalk at one time. Or Maybe a car drove on it.
Look
at this crack. To me it is a good example of normal faulting with the
hanging wall to the top and the footwall to the bottom. Here's another
example of faulting with the tree roots being the cause for the uplift
of the hanging wall.
I
then like to see the layering of sediments on top of the concrete. And
how in the lows the water has a tendency to accumulate the muds and
such which then can harden. I also like looking at how the redish sands
are heavier and settle out then with the less heavy dark organic
material on top.
Some times you can see imprints in the mud/ graywacke material.
Which
reminded me also of these photo where there were dog prints in the
sidewalk. My dog was kind enough to provide a scale for those dog
imprints. He's about 10 lbs.
Another imprint that I liked seeing was these:
I
thought they were really neat to see. I saw this section of concrete
as it was being poured. It started to rain really heavy as they were
finishing up. The striations across were done with the broom but the
round circular marks are from the rain drops.
On 6-18-13
which was after I did this post we got some very heavy rain. As I
walked after the rain I couldn't help but to notice the rain drop
imprints on some sidewalks. When the stuff is still damp that's when
you really notice it.
This 1st one isn't very in focus but you can get an idea as to how big the raindrops were - there is a dime for scale.
This was almost all organic debris from the rain.
Different side walk with more of a sandy underneath and less organic material.
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| raindrop imprints on a sidewalk |
But I thought it was also interesting to see after
it had dried in some
places too and the matrix was more sandy than organic material (which
also lead to its drying faster). I always think of 'The present is the
key to the past' and
if you can see things in the present you know what you maybe seeing when
you look at past rocks.
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| raindrop imprints on a sidewalk |
Here's another interesting one.
I
like to think of this as an igneous dike cutting into the sidewalk and
driveway. It fun trying to figure out the sequence of events. First
there was the driveway to the NW corner. Then came the sidewalk to the
SE. The there was fill in in the SE corner and the last was the W
central driveway material added to make a circular driveway.
Some
times the side walks act as conduits for water. This to me looked like
a natural spring but in reality it was a hose that had been left on to
water a plant.
A channel is being formed. There is so much that can be said about water and water features that I'm going to skip them.
And sometimes you can see ripple marks in the street concrete.
And sometimes you can see graded bedding going on, with the courser grains on the bottom and the finer ones near the top.
I could go on and on about the rocks in the concrete but there isn't enough room to write about all of that.
One of the things I was not expecting to see but was just too cute not to take its picture was this baby blue jay.
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| baby blue jay on sidewalk |
I
couldn't tell if its wing was damage or what but it sure did favor the
wing over the other as it was hopping/ flying trying to get away.
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| baby bluejay |
I was just glad this bird wasn't at my house because here's what I have staying by my front door all the time.
And here's Evelyn's cat picture.
I
always thought he was trying to do a good job demonstrating
stalagmites (rising from the cave floor) and stalactites (hanging from
the cave's ceiling).
Now I wish I could have that Slurpee I was thinking about earlier.
