# What is happening with these cliffs? (photo) **URL:** \ **Category:** Factual Questions\ **Created:** [October 3, 2007, 4:13pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399 "2007-10-03T16:13:45Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![vetbridge](https://avatars.discourse-cdn.com/v4/letter/v/b5e925/32.png) [@vetbridge](https://boards.straightdope.com/u/vetbridge)\ **Post date:** [October 3, 2007, 4:13pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/1 "2007-10-03T16:13:45Z")
I kayak on a [reservoir](http://www.lrp.usace.army.mil/rec/lakes/loyalhan.htm) sometimes. I was wondering about [these](http://s153.photobucket.com/albums/s218/vetbridge/?action=view¤t=cliffs2.jpg)[cliffs](http://s153.photobucket.com/albums/s218/vetbridge/?action=view¤t=cliffs-1.jpg) Being a flood control area, the depth varies a bit. The pics are from a day when the water was very [high](http://s153.photobucket.com/albums/s218/vetbridge/?action=view¤t=creepy.jpg), yet I have seen it at least 6 feet higher. Is the pattern solely from erosion? I have never seen an animal, other than some huge spiders, on these rocks, yet the areas look inviting to animals. I think the rock is limestone or sandstone, but I am no geologist, and this is just something I’ve heard. Extra credit: Find the [bird](http://s153.photobucket.com/albums/s218/vetbridge/?action=view¤t=findbird.jpg)! 😃 Thanks ---
**Author:** ![Santo\_Rugger](https://avatars.discourse-cdn.com/v4/letter/s/e95f7d/32.png) [@Santo\_Rugger](https://boards.straightdope.com/u/Santo_Rugger)\ **Post date:** [October 3, 2007, 5:07pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/2 "2007-10-03T17:07:50Z")
From the picture titled “cliffs2” (these) link, the circular pockets look like places where volcanic ash and/or gas was trapped in the [tuff](http://en.wikipedia.org/wiki/Tuff) while the rock was forming. It doesn’t look like volcanic rock, though. ---
**Author:** ![Swallowed\_My\_Cellphone](https://avatars.discourse-cdn.com/v4/letter/s/9d8465/32.png) [@Swallowed\_My\_Cellphone](https://boards.straightdope.com/u/Swallowed_My_Cellphone)\ **Post date:** [October 3, 2007, 5:13pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/3 "2007-10-03T17:13:49Z")
[QUOTE=Pygmy Rugger] It doesn’t look like volcanic rock, though. [/QUOTE] The first picture does. Compare it to the pictures of the tuff cliffs at the [Bandelier National Monument in NM](http://en.wikipedia.org/wiki/Bandelier) ETA: Maybe the more slate-like look near the water’s edge was cause by more direct water erosion than what you get at places like Bandelier. ---
**Author:** ![Santo\_Rugger](https://avatars.discourse-cdn.com/v4/letter/s/e95f7d/32.png) [@Santo\_Rugger](https://boards.straightdope.com/u/Santo_Rugger)\ **Post date:** [October 3, 2007, 5:13pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/4 "2007-10-03T17:13:51Z")
Missed edit window: Although it does look similar to the cliff side on this page: [http://www.nps.gov/band/photosmultimedia/photogallery.htm?eid=166523&root\_aId=290#](http://www.nps.gov/band/photosmultimedia/photogallery%2Ehtm?eid=166523&root_aId=290#) titled “Upper Falls in Autumn”, which are volcanic. ---
**Author:** ![vetbridge](https://avatars.discourse-cdn.com/v4/letter/v/b5e925/32.png) [@vetbridge](https://boards.straightdope.com/u/vetbridge)\ **Post date:** [October 3, 2007, 5:23pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/5 "2007-10-03T17:23:19Z")
Hmm. I have never had an interest in geology, but the more I read in the links provided, the more interesting it is! Under sandstone in wiki: [![](https://en.wikipedia.org/wiki/File:Stadtroda_Sandstein.jpg) ](https://en.wikipedia.org/wiki/File:Stadtroda_Sandstein.jpg) and [![](https://en.wikipedia.org/wiki/File:Wall_Patterns.jpg) ](https://en.wikipedia.org/wiki/File:Wall_Patterns.jpg) Interesting! ---
**Author:** ![Swallowed\_My\_Cellphone](https://avatars.discourse-cdn.com/v4/letter/s/9d8465/32.png) [@Swallowed\_My\_Cellphone](https://boards.straightdope.com/u/Swallowed_My_Cellphone)\ **Post date:** [October 3, 2007, 7:06pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/6 "2007-10-03T19:06:08Z")
Before the board crashed, I was just about topost a picture of the tuff that is along the banks of the Colorado River in Arizona (Grand Cayon stuff). Where the water has eroded the tuff it does actually look a bit like slate. While travelling to do rock climbing and caving, I’ve seen some gorgeous formations created with volcanic rock. Ash flows are cool. ---
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [October 3, 2007, 7:33pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/7 "2007-10-03T19:33:52Z")
I saw similar erosion in Capital Reef National Park, in Utah (except that the rock was red). There were even some bird nests in the holes. ---
**Author:** ![Contrapuntal](https://avatars.discourse-cdn.com/v4/letter/c/e274bd/32.png) [@Contrapuntal](https://boards.straightdope.com/u/Contrapuntal)\ **Post date:** [October 3, 2007, 8:02pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/8 "2007-10-03T20:02:34Z")
[QUOTE=vetbridge] Extra credit: Find the [bird](http://s153.photobucket.com/albums/s218/vetbridge/?action=view¤t=findbird.jpg)! 😃 [/QUOTE] Looks to be a heron or crane pretty much dead center. ---
**Author:** ![Nametag](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nametag/32/406_2.png) [@Nametag](https://boards.straightdope.com/u/Nametag)\ **Post date:** [October 3, 2007, 8:39pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/9 "2007-10-03T20:39:32Z")
The website (first link in the OP) says the cliffs are sandstone. It’s not unusual for sandstone to weather in layers, as it’s a sedimentary rock which deposits in layers of varying grain size and matrix composition. The bubbles might just be…bubbles; sandstone forms from mud, and can contain bubbles from air trapped in the mud. IANAG, though. ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [October 3, 2007, 10:00pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/10 "2007-10-03T22:00:18Z")
It looks like sandstone you see in Wisconsin. Often it’s recessed in an undercut, so the drip line is many feet beyond the wall. The outer layer can have a hard coating, and finding holes in it is possible. ---
**Author:** ![Edward\_The\_Head](https://avatars.discourse-cdn.com/v4/letter/e/ce73a5/32.png) [@Edward\_The\_Head](https://boards.straightdope.com/u/Edward_The_Head)\ **Post date:** [October 3, 2007, 10:08pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/11 "2007-10-03T22:08:00Z")
It might be some sort of [karst](http://en.wikipedia.org/wiki/Karst) topology. The wiki says that there is some in Central PA. ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [October 3, 2007, 10:20pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/12 "2007-10-03T22:20:56Z")
I can’t find what I wanted to show. The sandstone erodes out faster than the veins of quartz and iron or lead and you get ribbon effects on the cliff face. It’s not unusual to find hollow pockets in the sandstone with quartz crystals lining or filling them. ---
**Author:** ![Nametag](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nametag/32/406_2.png) [@Nametag](https://boards.straightdope.com/u/Nametag)\ **Post date:** [October 4, 2007, 1:11am UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/13 "2007-10-04T01:11:00Z")
There is some karst in south central PA, in the Appalachian Mountain Section, though not as much as in the Great Valley and Piedmont Lowlands. Loyalhanna Lake, however, is in southwestern PA, in the Pittsburg Lowland Section, which is wholly distinct from from the karst region. ---
**Author:** ![Nametag](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nametag/32/406_2.png) [@Nametag](https://boards.straightdope.com/u/Nametag)\ **Post date:** [October 4, 2007, 1:30am UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/14 "2007-10-04T01:30:18Z")
Here, by the way, are some of the references I’ve found: > **[DCNR Homepage](https://www.dcnr.pa.gov/Pages/default.aspx)** > > Learn about conservation practices on Pennsylvania public lands and outdoor recreation, education, and business opportunities in Pennsylvania state parks and forests. [http://www.libraries.psu.edu/emsl/guides/X/explanation.htm](http://www.libraries.psu.edu/emsl/guides/X/explanation.htm) > **[DCNR Homepage](https://www.dcnr.pa.gov/Pages/default.aspx)** > > Learn about conservation practices on Pennsylvania public lands and outdoor recreation, education, and business opportunities in Pennsylvania state parks and forests. “Loyalhanna,” BTW, is a hard name to research in PA geology, as Loyalhanna Creek and Loyalhanna Lake are a bit distant from Loyalhanna Gorge (where US Route 30 runs), and then there’s the “The Mississippian (Chesterian) Loyalhanna Member of the Mauch Chunk Formation,” which runs all the way into the friggin’ Alleghenies. All connected, of course, but when you’re trying to find out whether there’s limestone _here_, and the literature tells you there’s limestone in this other place by the same name… ---
**Author:** ![vetbridge](https://avatars.discourse-cdn.com/v4/letter/v/b5e925/32.png) [@vetbridge](https://boards.straightdope.com/u/vetbridge)\ **Post date:** [October 4, 2007, 4:19pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/15 "2007-10-04T16:19:17Z")
[QUOTE=Contrapuntal] Looks to be a heron or crane pretty much dead center. [/QUOTE] hehe. Yep, a great blue heron. I followed him around all day. **Nametag** thanks for the links. I never thought geology could be so interesting! **Harmonious Discord** , **Edward The Head** , **panache45** , **Swallowed My Cellphone** , **Pygmy Rugger** : Thanks to everyone for the info. Hope to see you on the water!! Also, I spoke with a park ranger at [Crooked Creek Lake](http://www.lrp.usace.army.mil/rec/lakes/crookedc.htm) yesterday evening and he confirmed with 100% certainty that the cliffs are sandstone. His cite was conversation with other rangers. ---
**Author:** ![Solfy](https://avatars.discourse-cdn.com/v4/letter/s/848f3c/32.png) [@Solfy](https://boards.straightdope.com/u/Solfy)\ **Post date:** [October 4, 2007, 4:50pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/16 "2007-10-04T16:50:05Z")
**Vetbridge** , have you ever visited Laurel Caverns? Their interior reminds me of your cliffs. It looks to be the right area, too. Since the rangers were so confident that it’s sandstone, it might be Pottsville, which is full of caves (which to my mind would make it soft and prone to forming what you saw): “Pottsville Sandstone. This sandstone is of Pennsylvanian age and occurs just above the Mauch Chunk formation. It has two sublayers: the Homewood Sandstone and Connoquenessing Sandstone. Both are massive cross-bedded layers containing plant fossils. Well-known outcrops of Pottsville Sandstone include Elk Rocks in Fayette County, Beam Rocks in Somerset County, and Wolf Rocks in Westmoreland County.” [Cite](http://www.karst.org/geology.htm) I’ve always had a soft spot for physical geography. ---
**Author:** ![vetbridge](https://avatars.discourse-cdn.com/v4/letter/v/b5e925/32.png) [@vetbridge](https://boards.straightdope.com/u/vetbridge)\ **Post date:** [October 4, 2007, 6:21pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/17 "2007-10-04T18:21:34Z")
[QUOTE=Solfy] **Vetbridge** , have you ever visited Laurel Caverns? Their interior reminds me of your cliffs. It looks to be the right area, too. [/QUOTE] I take my kids there almost every year. Very cool caves. ---
**Author:** ![Green\_Cymbeline](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/green_cymbeline/32/9244_2.png) [@Green\_Cymbeline](https://boards.straightdope.com/u/Green_Cymbeline)\ **Post date:** [October 4, 2007, 8:10pm UTC](https://boards.straightdope.com/t/what-is-happening-with-these-cliffs-photo/421399/18 "2007-10-04T20:10:53Z")
Looks like a lovely great blue heron. How pretty!