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5A


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by MV teacher: Mrs. B - Grade 5 (2010-2011)


Assignments
5A - Doctor Reports 05/17
5A - Expository Test (Listening) 03/28
5A - Mrs. Branch 03/28
5A - So Much Depends Upon 03/28
5A - Poetry 03/28
5A - My Most Honest Moment 03/18
5A - Heart Dissection 03/28
Reading Reflections 03/14
5A - I Am From 03/18
Français - cent mots 03/15
5A - 1st Expository Text 02/17
5A - Ramlieh Reflection 01/15
5A - Personal Narrative 12/09
5A - Place Value Voki 11/27
5A - Number Line 11/30

Blog Entries
4/5 I Am From
4/5 Good Manners
4/1 So much depends upon
4/1 Honest moment
4/1 Heart dissection
2/17 Rock Bridges
11/30 My Math Number Line
11/2 My Reading Log Wordle

List 25, 50, all

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Rock Bridges


Rock Bridges; A creation by the force of nature!


 


A landform unlike any other, an unusual one if that’s how you want to say it. It’s a landform found mainly in dry places. Rock bridges! They look like they were made by man, but they are actually made by the force of nature.


What do they look like?


 


A rock bridge looks like a large half circle sitting on the ground with a big hole in the middle. Rock bridges look to me like two things. 1-They look a bit like donuts because of the whole that is placed right in the middle. 2-They look also like rainbows because they are shaped like an arch. But as you know everyone can have their own opinions.


Weathering (when rocks get broken into smaller pieces) starts the whole thing, then comes erosion, then comes a natural rock bridge. Natural rock bridges and arches (same thing) are usually formed in deserts by erosion which is caused by moving water and sand in the wind. Most rock bridges over thousands of years become narrower from rivers, which very slowly wear down and cut under these red and orange cliffs made out of sandstone. Wind and rain slowly start making tiny holes in the cliffs. Then after a while, the holes get bigger, and after that even bigger until a big hole is formed in the middle, so that it forms an arch. Sometimes, when sinkholes form, some of the cave roof does not tumble down; this can also create a rock bridge. Some rock bridges may look a little bit like arches, but they form into the path of streams that wear away and penetrate the rock. Pothole arches form by chemical weathering, when water collects into pools and eventually cuts through to the layer below. I have seen them myself, which is in the Arches National Park in Utah (U.S.). I thought they looked really cool. Let me tell you the exact steps of how they are formed. 


Deep cracks cut into a sandstone layer.


Erosion wears away upper layers of rock and then enlarges the surface cracks, creating narrow sandstone walls, or fins. Changing frosts and defrosts causes crumbling the sandstone and after a while cuts through some of the fins.


Where do you find them?


Rock bridges are found where cliffs are face to erosion from the sea, rivers or wind and weather. Whatever they’re made from determines where they are found. They are usually found near seas or rivers, or in open areas like deserts. For example, in Utah most of them are made by wind. Therefore they are found in a desert of Utah.


What’s the most famous one?


Of all of the arches throughout the world, the delicate arch is by far the most recognizable. It is located in Arches National Park which is in the United States. This sandstone arch is 52 feet tall. It is so famous that it appears on the license plates of cars in Utah.


 


Like I said before, rock bridges are formed by erosion. It may occur that the erosion would keep on eroding away small particles from the sides of the arch. Sooner or later the sides would get so thin that they would not be able to support the top. As a result the bridge would collapse. The holes become bigger to arch proportions by rock falls and weathering. The arches eventually fall down; leaving only buttresses that in time will erode.


You now know how rock bridges are formed. You also know where you find them and how they look. I suggest know, since you know all about rock bridges to go and see them for yourself. Go and see a landform that you will never forget how cool it looks. Rock bridges!!!


 



 

Article posted February 17, 2011 at 04:41 AM • comment • Reads 1046 • see all articles

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