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Drill marks in rock walls? Scenery and structures
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MRH Author 5,531 posts Michael Tondee MRH Author 5,531 posts
Michael Tondee

Sometimes when traveling down the road, especially in mountainous regions, I will see exposed rock faces where the rock had to be blasted away in order to make way for the road. Many times I've seen long vertical lines going down the rock faces. My late Father had always taught me that those marks were from where the rock was drilled down into so dynamite could be lowered in and detonated in order to blast away the rock. Like many things you hear from your parents, I had no reason to doubt this information and took it as fact  and to this day I'm operating on the assumption that its true.  I would assume that a railroad would blast away rock for the right  of way with the same process but it occurs to me that I don't very often see it modeled. So is that the way it 's done?  Would there be some type of time frame that these lines would appear? In other words, was it done differently in earlier times?  I'm getting ready to do preliminary work on a model of a bit of a somewhat vertical rock face and I'm curious.

Michael

Michael, A.R.S. W4HIJ

 Model Rail, electronics experimenter and "mad scientist" for over 50 years.

Member of  "The Amigos" and staunch disciple of the "Wizard of Monterey"

My Pike: The Blackwater Island Logging&Mining Co.
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HVT Dave Prolific poster 1,213 posts
HVT Dave

Depends on the rock

Some rock is soft enough or fractured enough that it can be removed with a Caterpillar or track hoe, some needs to be drilled and blasted. 

Dave

Dave

Member of the Four Amigos

 
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salty4568 Regular poster 165 posts
salty4568

Drill marks

Era will make some difference .... in the 1800s it would be done with hand drills and sledge hammers, so they would be quite a bit shorter. Later air powered drills came along and they could drill much deeper holes, usually at least about 20 feet. With new core drills they can even go a lot deeper. 

Skip

 

Skip Luke
Retired Railroader
washington State
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locoi1sa Regular poster 310 posts
locoi1sa

Lots of variables here.

  Depending on the rock too. Granite dimensioned stone quarries would not blast the blocks out of the bench(place they get the product from). Drilled and split with wedges is the most common and then you would see the drill holes left in the bench. Blasting usually eradicates the drill marks and will no longer be visible. We once had a quartz rock estimated at over 90 yards that was impervious to a 10,000 lb hydraulic hammer. It was finally drilled like a postage stamp and a cracking agent poured into the holes and left over night. The next morning the rock was split into several smaller pieces that went into the jaw crusher with little effort.

 Dexpan cracking agent.  http://www.dexpan.com/dexpan-how-to-use-dexpan-non-explosive-controlled-demolition-agent-breaking.aspx

       Pete
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Brent Ciccone Brentglen MRH Author 980 posts
Brent Ciccone Brentglen

Check Road Cuts

Have a look at any rock cuts along the highway, you can often see the drill lines. More noticeable on more recent construction. I suspect as the rock face ages these lines tend to wear off as the rock face slowly disintegrates.

 

Brent

Brent Ciccone

Calgary
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