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Photo of north face of quarry
A well known geologist paces the length of the small quarry exposure. Here there is folding of various shapes.

Folds in a small abandoned quarry At location 10 there is a small area of flat ground which may be an abandoned quarry. On the south side the near vertical rock face reveals a schistose rock type with clear lineations indicating a pronounced cleavage. Most striking are the folds which are so tight that they have limbs on opposite sides of the fold which are parallel (isoclinal folds). The orientation of the folds are such that the hinge trends (direction as seen from above in plan view) N20E and a plunge (tilt downwards) of 45 degrees. On the north side of the quarry, some 20m away the rocks are also folded with open folds (0-30 degrees between limbs). These folds are likely to be a response to high compressional stress (squeezing force) resulting in shortening strain (movement) so that the layers of the rock are crumpled.

Photo of nort face of quarry

Geology students sketching.
The metamorphic grade is variable with low-grade on the north (the open folds) and higher grade schists on the south side (the isoclinal folds). The difference between the fold types may be due to the likely difference in ductility between the rock types with schist having a high ductility due to the high proportion of the slippery platy crystals of muscovite (a type of mica). This is also an example of the variability of the metamorphic grades with strain shadows likely.

photo rocks in quarry

The folds on each side of the quarry are at different angles shapes and are of different shapes.
close up of isoclinal fold
These folds are so tight that they have opposite limbs which are parallel.

Photo isoclinal foldsThe hammer is being held at the angle of the hinge of the fold angle.


The end of our tour
Here the flat ground is inviting us to sit down, have a rest and maybe a picnic, so treat yourself to some refreshments. You can ponder on our journey back in time and underground and to the many changes in the rocks we have witnessed. Maybe we understand a little more about what happens when rocks become buried and metamorphosed.

I hope you have enjoyed our journey and that we might meet again.

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