elizabeth

26 May 2017 149 views
 
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photoblog image Bridges vs Arches

Bridges vs Arches

The difference is in how the formation is created.

Narural arches are weather eroded,

Natural bridges are water eroded.

 

Weather eroded arches begin their formation as deep cracks which

penetrate into a sandstone layer. Erosion occurring within the cracks

wears away exposed rock layers and enlarges the surface cracks

isolating narrow sandstone walls which are called fins. Alternating frosts

and thawing cause crumbling and flaking of the porous sandstone and

eventually cut through some of the fins. The resulting holes become
enlarged to arch proportions by rockfalls and weathering. The arches

eventually collapse leaving only buttresses that in time will erode.

 

Some natural bridges may look like arches, but they form in the path

of streams that wear away and penetrate the rock. Pothole arches
form by chemical weathering as water collects in natural depressions

and eventually cuts through to the layer below.  The rock is typically

a much harder material than the soft sandstone of the arches.

 

Bridges vs Arches

The difference is in how the formation is created.

Narural arches are weather eroded,

Natural bridges are water eroded.

 

Weather eroded arches begin their formation as deep cracks which

penetrate into a sandstone layer. Erosion occurring within the cracks

wears away exposed rock layers and enlarges the surface cracks

isolating narrow sandstone walls which are called fins. Alternating frosts

and thawing cause crumbling and flaking of the porous sandstone and

eventually cut through some of the fins. The resulting holes become
enlarged to arch proportions by rockfalls and weathering. The arches

eventually collapse leaving only buttresses that in time will erode.

 

Some natural bridges may look like arches, but they form in the path

of streams that wear away and penetrate the rock. Pothole arches
form by chemical weathering as water collects in natural depressions

and eventually cuts through to the layer below.  The rock is typically

a much harder material than the soft sandstone of the arches.

 

comments (19)

  • Martine
  • France
  • 26 May 2017, 00:34
Les gens ne paraissent pas plus grands que des fourmis.
Elizabeth Croston Buckalew: And it's very much how we feel!
  • Ray
  • Not in United States
  • 26 May 2017, 00:35
This one might be a brarch, then?


Lovely picture, Elizabeth.
Elizabeth Croston Buckalew: smile Definitely a bridge, Ray!
I thought they were built by Native Americans! smile
Elizabeth Croston Buckalew: Well... native, anyway!
  • Jennie
  • United States
  • 26 May 2017, 04:21
So many textures and colors captured.
Elizabeth Croston Buckalew: Oh, Jennie - Southern Utah is so full of amazing places! I hope you can visit one day! I'll take a week off and be your guide! smile
  • Astrid
  • Netherlands
  • 26 May 2017, 04:44
The people really give scale. This is wonderful. Thank you for the write up. Wonderful picture.
Elizabeth Croston Buckalew: I was pleased the Dad stopped there to show his son how grandiose it all is.... made a better photo for me! smile I'm glad you enjoyed this post. I continue to be amazed at what I learn about the are!
After all the early morning education, Elizabeth, I'm delighted to see scale by the people in this image!
Elizabeth Croston Buckalew: smile I won't even test you later! smile
Yes - I'm so happy they stopped right there in their brightly colored jackets!
  • Chris
  • England
  • 26 May 2017, 06:22
This whole process must take thousands of years
Elizabeth Croston Buckalew: You are correct, sir. From the National Park Service:

"Sipapu is the largest and most spectacular of the three bridges in the Monument. It is considered middle aged, older than Kachina but younger than Owachomo. Its rounded opening and smooth sides are mute evidence of countless floods bearing scouring rocks and sand. This bridge, whose opening would almost house the dome of the United States Capitol, has taken thousands of years to form but will someday collapse and erode as part of the endless cycles of time and change.

Height: 220 feet (67 m)
Span: 268 feet (82 m)
Width: 31 feet (9.5 m)
Thickness: 53 feet (16 m)
  • Lisl
  • Bath, England
  • 26 May 2017, 06:32
That is all very interesting, Elizabeth
Elizabeth Croston Buckalew: I find it all so fascinating, Lisl - here's some more info I found for Chris:

"Sipapu is the largest and most spectacular of the three bridges in the Monument. It is considered middle aged, older than Kachina but younger than Owachomo. Its rounded opening and smooth sides are mute evidence of countless floods bearing scouring rocks and sand. This bridge, whose opening would almost house the dome of the United States Capitol, has taken thousands of years to form but will someday collapse and erode as part of the endless cycles of time and change.

Height: 220 feet (67 m)
Span: 268 feet (82 m)
Width: 31 feet (9.5 m)
Thickness: 53 feet (16 m)
Immensité vraiment superbe !
Ces falaises sont vraiment magnifiques !
Merci
Elizabeth Croston Buckalew: Thank you, Claudine! I just find it all so incredible! But, you all must be getting tired of seeing Southern Utah after I've been posting for 5 weeks! I'll move on soon!
Thank you for that description Elizabeth.
Elizabeth Croston Buckalew: You're welcome, Chad! I enjoy looking these things up! I found some more info for Chris:

"Sipapu is the largest and most spectacular of the three bridges in the Monument. It is considered middle aged, older than Kachina but younger than Owachomo. Its rounded opening and smooth sides are mute evidence of countless floods bearing scouring rocks and sand. This bridge, whose opening would almost house the dome of the United States Capitol, has taken thousands of years to form but will someday collapse and erode as part of the endless cycles of time and change.

Height: 220 feet (67 m)
Span: 268 feet (82 m)
Width: 31 feet (9.5 m)
Thickness: 53 feet (16 m)
  • Alan
  • Carlisle
  • 26 May 2017, 07:46
Thank you for your fascinating explanation (and also your comment on a previous posting about this). I got an impression of the size but then I saw the people and then got a very different realisation. It is HUGE. .
Elizabeth Croston Buckalew: It's so hard to convey the scale of these places, as you well know, Alan! So I'm glad they stopped in their brightly colored jackets! smile Here's some more info:

"Sipapu is the largest and most spectacular of the three bridges in the Monument. It is considered middle aged, older than Kachina but younger than Owachomo. Its rounded opening and smooth sides are mute evidence of countless floods bearing scouring rocks and sand. This bridge, whose opening would almost house the dome of the United States Capitol, has taken thousands of years to form but will someday collapse and erode as part of the endless cycles of time and change.

Height: 220 feet (67 m)
Span: 268 feet (82 m)
Width: 31 feet (9.5 m)
Thickness: 53 feet (16 m)
Well that is something I didn't know that I didn't know.

Nice picture with the people very kindly giving it scale
Elizabeth Croston Buckalew: And you'd-a been fine had you never known it! smile

Thank you, Bill!
The man and boy certainly give it scale!
Elizabeth Croston Buckalew: I was really pleased they stopped there for a moment!!
You and Frank are giving me the best illustrated Geology lesson ever, what magnificent work nature has done here.
Elizabeth Croston Buckalew: I'm so happy for that! I've learned so much, myself!!
oh i did not know there was a difference, Elizabeth. what a stunning image.
Elizabeth Croston Buckalew: I didn't either, Ayush!! I've learned so much. Thank you!
This is great, Ell'...The couple give it scale so well.
Elizabeth Croston Buckalew: Thank you, Frank! I was so happy they stopped there for a moment!
  • Anne
  • United Kingdom
  • 26 May 2017, 15:02
It's hard to find the words to express how wonderful this looks. I just cannot imagine what it must be like to actually be there to see it!
Elizabeth Croston Buckalew: I do hope you and Quinn can come out for a visit sometime, Anne! We'll be happy to guide you! smile
The sandstone making a frame for the people and tree are fantastic.
Elizabeth Croston Buckalew: It worked out pretty nicely, I was happy to see! Thank you, Mary!
  • Steven
  • Chicagoland
  • 30 May 2017, 03:06
A beautifully-framed view!! I never knew there was a difference. Thanks for the explanation! It makes sense!
Elizabeth Croston Buckalew: Thank you so much, Steven! I've learned a lot of geology from this little one week trip!

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