Ridge-Top Graben

Ridge-Top Graben

Most of you have probably noticed and some have pitched their tent in such "ridge trenches" usually called ridge-top grabens by geologists, i.e. longitudinal cracks or structural hollows at the top of a ridge that have developed over time into several-meter-deep ditches. Some can result from (or can be initiated by) gravitational forces pulling the rock mass in opposite directions. This nice one runs along the Polish-Slovak border, at the saddle NW of Starorobociański Wierch (Klin). It's a late September afternoon: warm in the sun on the south slope whereas frost holds on the shaded north slope. (Please see the comments below for a little discussion)
on Dec 18, 2008 2:05 pm
Image Type(s): Hiking
Image ID: 473048


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Tomek Lodowy

Tomek Lodowy - Dec 18, 2008 6:49 pm - Voted 10/10

Beauty !

Great shot with beautiful light effects !

Long live Starorobocianski ! :)



yatsek - Dec 19, 2008 3:22 am - Hasn't voted

Re: Beauty !

Thanks Tomek. Took it with the old camera but the film was high-quality Japanese reversal stuff. Not 100% Stara Robota then :)
To non-Polish people,
The name of the peak relates to a neighboring valley whose name translates as Old Work and derives from silver mining in the 16th century.


lcarreau - Dec 18, 2008 8:59 pm - Voted 10/10

So ...

What I'm seeing is a natural trench running
down the mountain? What about the erosional
forces of water? Don't they play a major role
in tearing down this mountain? Is this mountain made of limestone & Dolomite? If it is, then it might have features such as underground caverns. There's a river or lake
at the foot of this mountain, right???


yatsek - Dec 19, 2008 2:55 am - Hasn't voted

Re: So ...

Precisely running parallel to the ridge just below the top of the (often gentler) slope--the position matters a lot. The combined action of snow, freeze-thaw and rainwater (and perhaps wind) weathers and deepens such trenches over time. They occur in carbonate rocks as well (then it's easy for the waste to vanish underground) but the kind you see in the picture is characteristic of metamorphic rocks such as gneiss or schist. Take a look at this

As to the rivers and lakes, right, that's this kind of scenery.


visentin - Dec 21, 2008 9:45 am - Voted 10/10


I recognize the ridge of Ornak ! Another visible "trench" is the one made by hikers :(


yatsek - Dec 21, 2008 9:57 am - Hasn't voted

Re: trench

Right, Eric. Sometimes they're coupled, just like hikers. And it might be that their debatable origin can be explained by ancient hiking having demarcated the line:))


yatsek - Dec 21, 2008 4:37 pm - Hasn't voted

Re: trench

And many thanks for linking with Ornak. It shows pretty well that what matters most is usually the geological structure behind the relief. One important point is that the crest is exposed to erosion and shows off what is buried by rock waste further down the slope.

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