Many of you have been out to the Black Hills. If you haven't (or if you can't remember what it is like), visualize the following scenario:
As you drive west from Rapid City, you notice a jagged stretch of sandstone peaks called the Hogback Ridge. After a short descent from those sandtone peaks, you come to an area comprised of another sedimentary rock, red shale, which makes a "Racetrack" around the Black Hills. If you keep driving west, there is a gradual incline made of limestone. This limestone formed 100-500 million years ago, from the shells of ancient marine animals. (Yes, we are still in the Black Hills of South Dakota.) Keep driving still, past this limestone plateau, and you will see the Central Crystalline Core of the Black Hills. This area is made of schist (a metamorphic rock) and granite (an intrusive igneous rock) that have aged for up to 2.5 billion years. The apparent color of this Central Core and the groves of Ponderosa Pine gave this area its name, the Black Hills. You might want to get out of the car and take a hike up to Harney Peak, the highest peak in between the Rocky Mountains and the Alps of Switzerland.
What are the events that led to the formation of these Black Hills? Why does it look the way it does? Like geologists, we will explore these questions today.
Please watch the "Formation of the Black Hills" vodcast at our wikispace (It's on the Unit 7 Page). Then answer the following questions in your blog response.
- Write a summary of how the Black Hills formed. What are the events that led to their formation?
- Would the Badlands exist if weathering/erosion had not taken place? Why/Why not?
- The major uplift of the Black Hills occurred 70 million years ago. What do you think that area of South Dakota looked like 40 million years ago? What do you think the Black Hills and Badlands will look like in another 40 million years?
34 comments:
1.The black hills were ounce in the ocean-the
sedimetery rocks that were packed togther with clay.
2.the badlands would not be there if it was not for weaterig
becuase they would not be that whore down.
3.south dikata was an ocean maybe because
we have very flat land and very tall ground and we have
sedimetery rocks.
1. A mass of molten rock began to rise and cooled whick then formed granite
2. no because all the weathering made it how it is
3. I think it was fairly low still and it will be a lot larger in 40 milion years
Layer of granite and schist r deposited ... Limestone is deposited on top of the granite and schist .. Red shale was deposited on top of the limestone.. Sandstone is deposited on the red shale.. Uplift happened and the rocks cracked and started to erode away ...
1. The black hills formed from plate
Techtonics. the plates pushed up against
Each other and formed the mountains
That we call the black hills.
2. The bad lands would not be there if
Weathering and erosion did not occur.
This is because heat made it all erode and
Weather away.
1. Molten rock cooled unevenly
2 I think that they wouldn't exist
3. They will be mostly gone because of erosion
1) layers of rock and plate tectonics formed them. Once all of this happened and weathering and erosion occured. Then the different layers of rock form. Over time these structures have been formed
2) no because the rock wouldn't of been formed like they are now.
3) they probably were just blocks and not carved like they are now. In the future more weathering and erosion will take place.
1.I think the black hills were formed by plate tectonics. Also layers of rock.
2.No, because erosion and weathering play a big role in the development of the black hills.
3. They probably were just mounds of rock. But later on weathering and erosion made it what it is today.
1 plate techtonics and layer of granite formed the core. After this, weathering and erosion took place. Because of this, the layers of rock form.
2 no because the rock wouldn't of been formed like they are now. This would cause the hills to be either flat or even more steep.
3 the Black Hills were probably a large plain. Then underneath in the earths core, the granite was starting to form
Ashley Zimmer
1. The Black Hills formed by the deposition and build-up of rocks.
2. No, the Badlands were formed by weathering and erosion!
3. The Black Hills were probably flat 40 million years ago, but they will probably be eroded in the next 40 million years.
1. The badlands were formed billions of years ago by weathering and erosion most Likely from water and glaciers I would guess.
2. I do not believe that the badlands would exist if there wasn't any weathering or erosion because that is how they were formed from millions and billions of years of weathering and erosion which gave it it's awkward shape.
3. 40 million years ago I am sure that there were still mountainous but not as big and had more water and in another 40 millions years I am sure hat tube badlands will be even more mountainous
The black hills formed by Rocks cooling together the events to the black hills are limestone and schist granite red shale sandstone.
2. No because weathering and erosion are a big part of the rock cycle so there would be nothing there.
3. They probably were not as tall as they are now they were maybe they 10,000 ft. I think they will be way taller and much bigger.
The Black Hills were formed from erosion, weathering, and deposition. Th different types of rock were layered from erosion; the weathering caused the rocks to become different rocks causing them to be layered with many differen types.
No the Badlands would not have formed if weathering and erosion never happened because erosion caused the rocks and paricles to move from one place to where the Badlands were formed. Weathering is needed because the rocks are broken down in different ways to create th Badlands making them what they are now.
70 million years ago South Dakota was pretty much flat. 40 million years ago South Dakota had a little uplift; not huge but inbetween medium and small. Another 40 million years ago there must have been just about maybe even bigger than the 40 million previous years.
1. The Black Hills formed by erosion and deposition.
2. No, the Badlands would be non-existing without it's erosion and deposition.
3. It was regrowing from the asteroid impact (which took place 65 million years ago from today. In the future, I am sure that some new sandstone and granite and shale will have formed. (Hopefully not from another asteroid impact!)
1. 2.5 billion years ago the black hills was by the see. Magma from the earths core cooled and became Schist granite. This was the center of the black hills. Limestone was deposited on top of the granite.Then other sedimentary rocks like red shale were deposited ont tops of the others. Another rock that was deposited is sandstone. Then uplift pushed all the rocks up to form a hill.
2. No it wouldn't because then it would just be a big rock. It would just be a big rock because weathering and erosion took away parts of the rock.
3. 40 million years ago i think it would just be a mountain be the see. Also, there would be dinosaures. 40 million years from now it might be gone because everything was eroded away.
1. It took millions and billions of years for the Black Hills to form. The metamorphic rocks were formed on the bottom of a shallow sea. It required a lot of heat and pressure. Granite was formed when molten rock began to rise from deep in the earth's crust. Many rocks have been eroded away like limestone. Many sedimentary rocks were deposited like red shale. The next sedimentary rock that was deposited was sandstone. Uplift made the sedimentary rock begin to crack.
2. No, because then the land would basically just be flat and there wouldn't be any mountain like structures.
3. I think back then it looked like a bunch of hills made of rocks and it didn't look anything like it does now. In the future I think it will really look like mountains as the uplift will countinue and there will be many more structures like the Badlands.
The black hills were formed by erosion weathering and deposion. Since it weathered different rocks. The different rocks layers layed down.
No because they were form from erosion and weathering. If there was none it would just be flat land.
It would look a little lower then what it looks like now. If you waited another 40 million years the granit would push up and poke out because of uplift.
1. The black hills formed from rocks stacking on top of each other and then they all uplifted to elevate the land.
2. No they would not exist if they werent weathering or erosion because erosion moved all of the rock over to the black hills so they could form.
3. I think that it was a lot smaller forty million years ago and I think they will be bigger in the future.
1. Different types of rocks formed or were deposited on top of each other and over time they became a bunch of layers, then an 'uprise' hapenedvcreating the hill structure. 2. No, they were a huge part in building them
1.) schist and granite formed the first layer and then limestone was deposited on it. Red shale then formed on it and following it is sandstone. Uplift is what happened to the layers causing it to rise and weather down.
2.)
1. Well, the main reason the black hills formed is from all the deposition layering on the black hills with additional types of rocks layering them
2. No, since weathering and erosion is the whole reason the black hills formed. Without the weathering of other rocks and erosion not able to take therocks to the blackhills
3. You can tell that it used to either be watery, or a tropical forest. Over the years though, it's going to keep getting dryer.
1. The black hills formed from sedimentary rock and overtime they uplifted and the bottom layers to the top.
2. No because without it the sediment never would've moved off the black hills in the first place
3.they probably ere very flat and didn't have a lot of rock formations. They migh look flatten out because of w & e or they could get higher because of it
1. The black hills were formed through weathering and erosion. Basically they started out as one, and over time, have developed certian shapes and sizes. They've done this through wind, heat, and pressure.
2. Yes, but they would not look the same at all. They started out underwater and since then have been worn away. So yes, they would still exist, they just wouldn't look anything like they do now.
3. I think 40 million years ago, south Dakota was probably completely underwater, along with many other states. In another 40 million years, for all we know now, it may be underwater again! Or there may be even more rock forms from weathering and erosion.
It started with schist rock. Then intrusive igneous rock created granite as it got older'. Then limestone was the next layer with deposition as it's cause. Red shale made up the next layer, with sandstone on top. These layers eroded and weathered through the years making the black hills what they are today. Different rocks weather at different rates.
Long ago, rocks were weathered and wind picked up the sediment. There it was deposited and over the years, many other layers of rock were deposited on top of the other layers. The top layers were eroded down, exposing the strong, resistant rock on the bottom.
1. The formation of the black hills is made from granite and shcist which is covered with limestone and which is covered by red shale and sandstone leading in an uplift
2.Yes because there is not much eroisen and weathering in the black hills.
3.In another 40 million years the black hills will be be filled with more minerals then right now
1. The formation of the black hills formed from metamorphic rock, schist then sedimentary and igneous rock is added granite, limestone, red shale, and sandstone and uplifted about 70 million years ago.
2. No the badlands would not be in existance if there was no weathering/erosion because the sediment flowed to the badlands area.
3. The black hill might have been flat ground 40 million years ago in 40 million years I think that the Blake hills will once again be flat land.
A looooong time ago, metamorphic rock formed as schisht.. Then granite came along. Next, some limestone was weathered from some other ricks and landed on the granite and schist! but, that wasn't good enough, so, some red shale came. Finally, the sandstone came and deposited on the hill. Uplift came along, and now schist and granite are the tallest points! Different rocks weather at difernt rates because, while schist And granite are very strong and stayed and slowly moved to the top, the sandstone, red shale and limestone were more weak so they weatherEd and eroded away, faster than the schisht and granite.
Long ago rocks it started with very old schist then granite came along, then some limestone came along, then some red shale, then lastly the sandstone came along, finaly erosion built it up to look like a mountain, after all these years weathering beat it down. It deppends on what type of rock is there because different rocks get broken down at different rates.
The black hills were formed about 2.5 billon years
By a couple of rocks that kept growing and
70 million years ago the black hills were
apart of a uplift and it is still going to this very day
No their would be a rock but yet I still
don't think it would be a badland for say
The badlands and mount rousmore will
most likely be a couple thousand feet
higher and I would count my self very
lucky to see what is like now
The formation of the black hills were made by shists and granite on the bottom and then the limestone was on top of that. After the second layer the 3rd layer was red shale and ontop sandstone. But it was much higher than it is today, so Now shist and granite are the highest because it's more resistant than all the others to weathering!
1) The Black Hills went through tons of weathering, erosion, and a lot of years to get to how it looks now. The Black Hills changed a lot since of how much weathering and erosion the huge rock has gone through.
2) The bad lands would not exist if there was no weathering or erosion because then the Bad Lands would just be a smooth flat rock with no significance. Weathering and erosion made the Bad Lands what it is today.
3) I think the Black Hills didn't look as bumpy and cracked as it does today. In 40 million years I think the Black Hills and the Bad Lands are gonna look so much cooler than they already do, because of all the weathering and erosion it has left to go through.
1. magma from under ground rose to the surface which forced all the minerals and rocks up creatin the hills
2. well in a sense no because it would really just be a big mountain instead of what it is now because the rocks wheather at different rates is why the black hills and the badlands are what they are today
3.40 million years ago the badlands would have been much larger than what they r today
1.it started with the medimorfic rock then it formed a intrisive igmois rock.then it went 2 a sedimentire rock thay were deposited on the black hill after all of tje diffrent kinds of sedimentiry rocks the black hills started 2 uplift from the magma. all of the rocks weather at diffrent rates that is y granit is now at the top when it was at the bottom at tje beging
2. no they wouldnt arleast i dont think but they might just not as big
3.i think it was al flat and knowone had any moutains around
If the Black Hills followed the normal course of rock formations, it started with the limestone. The rock (made of organic material) would have weathered and eroded, landed in the outer part of the Black Hills, and cemented and compacted into limestone. The schist would have started as a sedimentary or igneous rock, that was subject to extreme heat and pressure. It would change into schist and build up in the Black Hills. Next would be the granite, which would have started out in magma. It would melt, and become molten. Then, as an intrusive igneous rock, it would form within the Earth. It would cool, and also become part of the Black Hills.
2. If weathering and erosion were not a part of making the Black Hills, it might or might not be there. The limestone would not be, but depending on whether sedimentary rock was used in the making of the metamorphic rock or not would pretty much determine that.
3.They would probably look in better condition without all the years of weathering and eroding. In the future, they will probably look more worn down than ever.
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