When looking at a headstone we must make some observations. The first will be the composition of the headstone. The headstones in Evergreen Cemetery are composed of one of three rock types: igneous, sedimentary, or metamorphic.
The igneous headstones are composed of granite. Granite is an intrusive igneous rock so it is coarse-grained meaning the individual crystals can be seen with the naked eye. It has a crystalline texture which gives it a speckled appearance. Granite is often pink, black and white or white and black. Granite is quite resistant to weathering. Below is a photo of a granite headstone:
Next we have a close-up of a pinkish granite:
Now a close-up of a white and black granite:
The sedimentary rock most commonly used for headstones in Evergreen Cemetery is limestone. This rock is a biochemical sedimentary rock and it often appears to be made of shells and sand grains glued together. This limestone is a buff color and can also be seen in the columns of the KOM building. Stop and take a look the next time you're heading to class. Limestone weathers very easily and therefore is not used for headstones very often.
See below for photos of two limestone headstones. Note the weathered appearance of these headstones:
Headstones for Woodsmen of the World are often shaped liked trees and are made of limestone:
Next we have a close-up of limestone showing the shells and sand grains glued together:
The third rock type used for headstones is marble, a metamorphic rock. Marble is a non-foliated rock created by the metamorphism of limestone. Marble is soft and is often used in sculptures. It is often white in color and has a sugary appearance and it can be covered in lichen. Marble weathers easily and many old marble headstones are now illegible.
Below is a photo of a typical marble headstone, including lichen covering much of the headstone:
Next is a close-up of a marble headstone:
After determining the type of the rock used for the headstone we must then assess how weathered the headstone is. We use a scale to assess weathering and below are examples of each step on the scale:
1 - No indication of weathering
2 - Some weathering, but easily readable
Friday, February 3, 2012
Plate Tectonics Vacation Snaps
I don't really have any specific plate tectonics photos, but these two can be related to plate tectonics.
This photo was taken in Iceland. Iceland is located on a hotspot and on the Mid-Atlantic Ridge. I went on a research cruise that departed from Reykjavik. You can go see the Mid-Atlantic Ridge as a surface feature in Iceland. Unfortunately I was not able to do that as we had only one night in Iceland before the cruise left.
This photo was taken in Great Smoky Mountains National Park. This park is part of the Appalachian Mountain chain, which formed when the supercontinent of Pangaea was assembling in the Paleozoic.
This photo was taken in Iceland. Iceland is located on a hotspot and on the Mid-Atlantic Ridge. I went on a research cruise that departed from Reykjavik. You can go see the Mid-Atlantic Ridge as a surface feature in Iceland. Unfortunately I was not able to do that as we had only one night in Iceland before the cruise left.
This photo was taken in Great Smoky Mountains National Park. This park is part of the Appalachian Mountain chain, which formed when the supercontinent of Pangaea was assembling in the Paleozoic.
Plate Tectonics
This week in class we've been talking about plate tectonics. We started by discussing Alfred Wegener and his theory of continental drift. My personal blog is called Continental Drift and I have a "Stop Continental Drift" bumper sticker on my car so I'm a big fan of Wegener. He was a man ahead of his time and didn't live to see the acceptance of his theory. You can read about the reactions to his theory here and here. One of the important advocates of continental drift and plate tectonics was an Australia geologist, Samuel Warren Carey.
After continental drift we discussed seafloor spreading, proposed by Harry Hess. As Callan Bentley writes continental drift + seafloor spreading = plate tectonics. We have only just started discussing plate tectonics in class and talked about the lithosphere and the asthenosphere and divergent plate boundaries today. You can see some animations of plate tectonics, including divergent boundaries, here and here.
There is an interesting blog about using diamonds to date the start of plate tectonics. The isotopic dating of diamonds with eclogitic inclusions, which might be formed from partial melting during the formation of the coeanic crust, shows that plate tectonics may have started around 3 billion years ago.
I also found an interesting series of blogs about subduction denialism written by Brian Romans. You can read these posts here: part 1, part 2, and part3. I never knew there was such a thing as subduction denialism and they tie it in with the expanding earth theory. Part 2 of that series of posts has excellent topographic profiles of various subduction zones/deep ocean trenches.
After continental drift we discussed seafloor spreading, proposed by Harry Hess. As Callan Bentley writes continental drift + seafloor spreading = plate tectonics. We have only just started discussing plate tectonics in class and talked about the lithosphere and the asthenosphere and divergent plate boundaries today. You can see some animations of plate tectonics, including divergent boundaries, here and here.
There is an interesting blog about using diamonds to date the start of plate tectonics. The isotopic dating of diamonds with eclogitic inclusions, which might be formed from partial melting during the formation of the coeanic crust, shows that plate tectonics may have started around 3 billion years ago.
I also found an interesting series of blogs about subduction denialism written by Brian Romans. You can read these posts here: part 1, part 2, and part3. I never knew there was such a thing as subduction denialism and they tie it in with the expanding earth theory. Part 2 of that series of posts has excellent topographic profiles of various subduction zones/deep ocean trenches.
Tuesday, January 24, 2012
Vacation Snaps
In keeping with last week I thought I'd post some of my personal photos that fit the topic of the week. I might have a problem next week when we get to plate tectonics.
This is from Hawai'i. I was traveling up Mauna Kea. In the background you can see the big shield volcano of Mauna Loa and in front of that there are some small cinder cones.
This photo is from Volcanoes National Park. It is one of the coolest places I've ever visited. The dried lava was just amazing to look at. Behind me you can see the ropy Pahoehoe.
Looking down towards the ocean you can see the variety of lava flows from the colors of the dried lava.
Looking down on the Kilauea Iki crater. This was filled with lava less than 50 years before this photo was taken in 2007.
On the Kilauea Iki Trail that crosses the crater. It is amazing to walk across this crater and look at the dried lava and the plants now starting to grow in cracks.
A black sand beach on Hawai'i. You can see the olivine and basalt in the sand.
This is from Hawai'i. I was traveling up Mauna Kea. In the background you can see the big shield volcano of Mauna Loa and in front of that there are some small cinder cones.
This photo is from Volcanoes National Park. It is one of the coolest places I've ever visited. The dried lava was just amazing to look at. Behind me you can see the ropy Pahoehoe.
Looking down towards the ocean you can see the variety of lava flows from the colors of the dried lava.
Looking down on the Kilauea Iki crater. This was filled with lava less than 50 years before this photo was taken in 2007.
On the Kilauea Iki Trail that crosses the crater. It is amazing to walk across this crater and look at the dried lava and the plants now starting to grow in cracks.
A black sand beach on Hawai'i. You can see the olivine and basalt in the sand.
Igneous Rocks
This week in class we're covering igneous rocks and volcanism and on Friday we'll be discussing Geological Hazards. It should be a fun week.
We started Monday's class by talking about the rock cycle. You can watch a youtube video about the rock cycle here. There are a bunch of rock cycle songs, most of which are not very watchable. This is one of the better ones.
Moving on to igneous rocks, did you know that ice cream is an igneous rock? The Green Gabbro blog provides an excellent explanation. Now I'm hungry. I had a small tub of Ben and Jerry's stashed in the departmental freezer. I wonder if it's still there.
This is a really interesting post on cooling fronts in igneous rocks and also talks about Devils Tower and whether it is an igneous intrusion (yes) or a volcanic neck (no). I would really like to go to Devils Tower some day. It is amazing and I'd like to see it in person.
We started Monday's class by talking about the rock cycle. You can watch a youtube video about the rock cycle here. There are a bunch of rock cycle songs, most of which are not very watchable. This is one of the better ones.
Moving on to igneous rocks, did you know that ice cream is an igneous rock? The Green Gabbro blog provides an excellent explanation. Now I'm hungry. I had a small tub of Ben and Jerry's stashed in the departmental freezer. I wonder if it's still there.
This is a really interesting post on cooling fronts in igneous rocks and also talks about Devils Tower and whether it is an igneous intrusion (yes) or a volcanic neck (no). I would really like to go to Devils Tower some day. It is amazing and I'd like to see it in person.
Friday, January 20, 2012
Gold
To add on to my previous post I thought I would add a personal photo. In the summer of 2011 I took a trip to Georgia and stayed in the mountains in north Georgia. While I was there I visited Dahlonega, which is a cute little town that was the site of the first major gold rush in the US in 1828. While we were there my friend and I went panning for gold at one of the gold mines that operates tours. You're actually given the pan with the sediment already in it so I'm convinced that it's salted to make sure everyone can find a few specks of gold. I still have my small tubes with two tiny specks of gold at home.
Spring 2012
Once again I did not do a good job of updating last semester, but I'm trying again. This week was our first full week of classes, although classes did start last Thursday and we were off for Martin Luther King Day on Monday. This means that we've had the equivalent of one week of GEOL1030 classes. In our first week of classes we've discussed the scientific method and minerals.
I just read an interesting blog post (here) about conflict minerals. Gold, tungsten, tin and tantalum are minerals that are abundant in the Democratic Republic of Congo, an impoverished country that has been severely affected by civil war. Mining and trading of those minerals have helped fund the wars that have rocked DRC, but a new program will require US companies to certify with the SEC that any gold, tungsten, tin and tantalum acquired has not been used to fund conflict in DRC. I think this a great step to help resolve issues surrounding conflict minerals.
On a less serious note, go take a look at this huge ruby corundum collected from Maryland. Corundum, as discussed in class today, is a mineral that can be found in many colors and "forms", with both rubies and blue sapphires considered to be the mineral corundum.
I just read an interesting blog post (here) about conflict minerals. Gold, tungsten, tin and tantalum are minerals that are abundant in the Democratic Republic of Congo, an impoverished country that has been severely affected by civil war. Mining and trading of those minerals have helped fund the wars that have rocked DRC, but a new program will require US companies to certify with the SEC that any gold, tungsten, tin and tantalum acquired has not been used to fund conflict in DRC. I think this a great step to help resolve issues surrounding conflict minerals.
On a less serious note, go take a look at this huge ruby corundum collected from Maryland. Corundum, as discussed in class today, is a mineral that can be found in many colors and "forms", with both rubies and blue sapphires considered to be the mineral corundum.
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