Sunday, 8 January 2012

Holyrood again

Today I headed out to holyrood park for a climb on Haggis Knowe. I was still pretty tired from yesterday so I took my time waking up meaning that I didn't set off till quite late. I found a reasonably steep short wall over looking the road so I set off to boulder around on this.
The steep wall
I did a few traversy things and one short route which went up a vertical wall into a nice scoop with a small overhang above it. It was probably no harder than severe but pretty good fun.
There were lots of little vesicles, frozen air bubbles, around which had been infilled with either quartz or calcite. I presume its calcite but I didn't have any metal objects on me to actually check, calcite scratches but quartz doesn't.
I left the crag as soon the sun was starting to set and went for a walk around the park. On my way I had a look at the sill just below the long row. Its formed from micro gabbro and has some interesting features on its top surface. There are lots of parallel lines which to the untrained eye may be assumed to be glacial strai, thats what I thought they were to begin with, but are infact ripples at the hot magma was injected bettween layers in the rock.The photo below shows them, although they are hard to see.
Injection Ripples
On my way back I had a look at some sandstone at the end of the crags. I was going to take a picture of the sandstone-dolerite contact but instead I got distracted by some interesting features in the sandstone. Initially I saw some cross laminations but they weren't as obvious as another feature. Im not too sure exaclty what this feature is, although I have narrowed it down to either load casts of convolute laminations. What I am sure of is that they are examples of soft sediment deformation, so before the sediment has been fully lithified. I am also pretty positive that the sandstone I was looking at is of a sub-aqueos origin.
The sandstone as you can see in the picture is red and the grains were reasonably coarse.
Mystery sedimentary structures
Overlying this was a very light brown sandstone with smaller grains, possibly showing a change from a sub-aquean to a sub-aeolian environment. I will have to go back earlier in the day, with my hand lens, so I can see any structures, to make sure of this though.
On my way home I went into the CSE were Gerry was setting some boulder problems so I helped out. He set two routes using a total of five holds. One made the most of the features on the featured wall and the other was a bridging route up the chimney.

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