Fire Affects to Different Rock Types

With the recent firestorm that is still raging in Ventura County I am now more curious than ever as to how bad fire is for rock. What happens to sandstone vs granite vs limestone vs metamorphic etc.... I know we have had Santa Barbara bouldering hit with fires before but they seem ok now. Anyone have examples of areas that were once great but after fires are junk? Once damaged will they ever be the same? 

Icicle Creek Canyon outside Leavenworth would be a good case study for granite.  Fires pretty much torched the entire canyon in the early 90's.  I can't speak to what it was before but I bet you could track down some info on it.  

Good question! I'm guessing, even more than usual, the answer is "it depends".

Here, in Boise, the Tablerock fire was so hot on one side of the mesa it scoured every thing on the surface off the rock. Lichen, dirt, graffiti, the darker patina even. It was transformed to a pristine white above a sea of charcoal on the slopes below it.

On the other side, where it has been quarried and the land is flatter (climbing and bouldering), the rock is much the same as before. That side is heavily traveled (hiking, biking, and some climbers) and is mostly dirt.

My thinking is wetness will be a big part of it. Wet rock (back east, maybe Leavenworth?) that is heated rapidly, or, in drier areas, rock heated by fire suddenly hit with a few tons of water.

My thoughts are with you in CA. Fires hit so hard this year! We lucked out here, but it was purely that, luck.

Best, Helen

If it's a type of rock that water can seep into (most types of sedimentary rocks like limestone and sandstone), then intense heat from fire can damage it really badly.  Most of us who were boy scouts have probably experienced a damp rock exploding in the campfire before as the water inside it heats and expands.

But fire can damage more solid igneous rocks, too.  There was a big forest fire in a remote mountain range in Southern Utah years ago, and many classic granite boulder problems were destroyed, especially those that followed flake and crack features.

Also, the title of this thread should be EFFECTS (noun), not AFFECTS (verb).

Pnelson wrote:

If it's a type of rock that water can seep into (most types of sedimentary rocks like limestone and sandstone), then intense heat from fire can damage it really badly.  Most of us who were boy scouts have probably experienced a damp rock exploding in the campfire before as the water inside it heats and expands.

But fire can damage more solid igneous rocks, too.  There was a big forest fire in a remote mountain range in Southern Utah years ago, and many classic granite boulder problems were destroyed, especially those that followed flake and crack features.

Also, the title of this thread should be EFFECTS (noun), not AFFECTS (verb).

Damn it! I knew I should’ve gone with Effects. Lol. I swear I use to be able to edit the title of a post before. Now I can’t figure it out. When I’m on the webpage it automatically routes my forum page back to mobile. 

Joe Garibay wrote:

Damn it! I knew I should’ve gone with Effects. Lol. I swear I use to be able to edit the title of a post before. Now I can’t figure it out. When I’m on the webpage it automatically routes my forum page back to mobile. 

Joe, you have to be in your first post to edit the title. I just checked, and it worked on one of mine. But, I've not installed the app on my phone, so perhaps that's the problem.

I would point out, your word is correct if you changed the sentence structure. Thees people r picky.

Best, Helen

Old lady H wrote:

Joe, you have to be in your first post to edit the title. I just checked, and it worked on one of mine. But, I've not installed the app on my phone, so perhaps that's the problem.

I would point out, your word is correct if you changed the sentence structure. Thees people r picky.

Best, Helen

Like this?! Haha. I like to have good grammar but it’s not my passion

Joe Garibay wrote:

Like this?! Haha. I like to have good grammar but it’s not my passion

Yuz forgot the period on your sentence Punctuation police, ya know

It's sorta snowing here, and an otherwise cold, ugly, depressing, grey brown inversion has settled in. I'm doomed to the regular gym, housecleaning or errands. Woo. Hoo. Went to the indoor climbing gym yesterday, so that's out until Monday so my hands and knees can recover. 

Sucks bigtime being old... :-/

Joe, I really do think water would be the key. A fire isn't going to be hot enough to smelt rock, at least I don't think so, which leaves fire combined with something else to have an, uh, uh oh, effect? on the rock. Apart from burning off surface stuff, or depositing soot, etc on it, which would be cosmetic. 

All the tic marks could be erased. Tragic, that!

Best, OLH

Pnelson wrote:

Also, the title of this thread should be EFFECTS (noun), not AFFECTS (verb).

Except when effect is a verb and affect is a noun.

Y'all thread drifted so hard. 

I sent Joe a text this morning and told him we should've climbed a sandstone wall while we had the chance. Will this recover well? Should we treat all bolts in a sport area boasting sandstone, schist,and cobble conglomerate as suspect?

Jeff Luton wrote:

Y'all thread drifted so hard. 

I sent Joe a text this morning and told him we should've climbed a sandstone wall while we had the chance. Will this recover well? Should we treat all bolts in a sport area boasting sandstone, schist,and cobble conglomerate as suspect?

Jeff, I do hope some geologists show up.

I will say, Tablerock, mentioned above, is sandstone, although hardish sandstone. I don't see vertical faces or bolts affected much, if at all, as there likely won't be much there to burn.

Bouldering, maybe, but if it's mainly grass/brush that's burning, then it may simply bare more boulders.

Erosion would then become the big deal, as well as habitat restoration. It is totally reasonable to close an area for a season (or several) to get restoration work done.

Here, that's been a true community effort, with a big cross section of folks helping.

I can also report that the person who started the fire (illegal fireworks) is facing a $400,000 bill to pay for the firefight. That's not counting whatever happens in civil court, for the house that was lost.

Best, OLH (Shopping for more layers, since it's "feels like" 20 out)

Also, If the rock has a combination of poor thermal conductivity and high thermal expansion properties, the outer (hotter) layers will expand to the point that they break whatever bonds held them in place, irrespective of water content.

Gunkiemike wrote:

Except when effect is a verb and affect is a noun.

Um, yeah, this thread is not that type of case, and I'm pretty sure you know this.

Joe, what a terrible situation down in Southern California right now.  

Interesting question about how fire may effect different rock types.

Here is a link with some discussion and pictures of some of the crags up in Napa County at Mt. St. Helena after the Tubbs/northbay fires.  The rock here is volcanic that differs significantly from really hard to soft/mud, mostly depending on elevation on the mountain.

https://www.mountainproject.com/forum/topic/113732041/mt-st-helena-crags-fire-damage-updates

a thread on bolt damage from a fire in Poway.

https://www.mountainproject.com/forum/topic/106333899/burned-out-bolts

Elephant knob experienced rock damage. Granite.

https://www.mountainproject.com/area/105844887/elephant-knob

This is the area (Wheeler Gorge) your concerned about I’m guessing ? I passed through here last summer on 7/1/17. What a beautiful local climbing spot and condolences on what is likely to be a changed landscape there. 

I believe it has a lot to do with how hot it burns directly at the base of the routes, cliff angle, and expansion beneath the surface layers. 

As Darren (Splitclimber) says above our local cragging area (Mt. St. Helena) suffered significant rock damage on some of the most popular routes as a result of the October Tubbs Fire. The area where the routes were damaged remains closed for over one month with no re-opening in sight. Rebolting and extensive restoration may someday allow the routes to be climable again but for now it’s anybody’s guess when that will be. Good Luck and hopefully the area is Ok !

Eric Berghorn wrote:

This is the area (Wheeler Gorge) your concerned about I’m guessing ? I Visited here last summer on 7/1/17. What a beautiful local climbing spot and condolences on what is likely to be a changed landscape there. 

I believe it has a lot to do with how hot it burns directly at the base of the routes, cliff angle, and expansion beneath the surface layers. 

As Darren (Splitclimber) says above our local cragging area (Mt. St. Helena) suffered significant rock damage on some of the most popular routes as a result of the October Tubbs Fire. The area where the routes were damaged remains closed for over one month with no re-opening in sight. Rebolting and extensive restoration may someday allow the routes to be climable again but for now it’s anybody’s guess when that will be. Good Luck and hopefully the area is Ok !

Where was the second picture taken? Where the tubbs fire came through? That's so gorgeous.  :-/

Best, Helen

Those are both great shots of a now burned area outside ventura

Joe Garibay wrote:

Those are both great shots of a now burned area outside ventura

Ah, so, so, sorry! They both look interesting. 

CA has been hit hard, north and south, but many of us could have had just the same. With the record snowpacks, we were expecting a really bad year as opposed to just the new "normal bad" fire years.

At least the climbing areas may come back. Wildfires through towns? Super scary. Sooooo could be Boise, and so many other places.

Best, Helen

Joe Garibay wrote:

 I know we have had Santa Barbara bouldering hit with fires before but they seem ok now. 

Same with Black Mountain on San Jacinto, although that fire was decades ago and burned all but the largest pine trees there. Pink Crack and Tour de France are only pink because they're stained with fire retardant. 

I'm hoping the same will be true of Pine Mountain if it gets that far north. I know that area has burned some time in the past, before it was developed in the 90s. But hopefully they can stop it at the Sespe River before it gets near there.

Sespe Gorge doesn't have a lot of vegetation on it, so hopefully that will be ok. 

Maybe the fire will even open up some new areas, or at least make the approach to Matilija Wall less heinous. 

All the main climbing areas around SB and Ventura have had fires in the past without significant damage to the rock. In fact, as noted by someone above, brush clearing fires will tend to make it much easier to access certain formations that are very difficult to bushwhack to through the overgrown brush. Right now lets just keep our fingers crossed that the fire doesn't blow downhill into Santa Barbara and Montecito in the next couple days.