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The Gorges d'Héric
About 100m further up the gorge along
the narrow road to Héric which follows closely the Ruisseau
d'Héric. For the most part, the rocks are similar to those
at location 1, but have changed in orientation.
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The orientation of the rocks.
The difference here is that the planes
of foliation have swung round to have a strike of E50N with a dip
not quite as steep as before at 60 degrees towards the SE.. This may
be due to either our location further into the dome where the orientation
of the strata are on average more horizontal, or to large folds in
the rock strata. There is no way of telling with the evidence in front
of us. |
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| A closer view |
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| A geology student hard at work
in front of the low grade schists which here are hardly metamorphosed
at all. |
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2-3m dyke
There is a much larger dyke of pegmatite at this location varying
between 2m and 3m thick within the low grade metamorphic psammite.
Set in the pegmatite are small dark green tourmaline crystals about
5 mm across. They are well formed (euhedral). Their hexagonal prismatic
shape can be clearly seen.
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| A close up view of the texture showing poorly
formed and not very regular microfolds. |
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| In a similar dyke a few metres further up
there are blocks of the schist within the pegmatite (xenoliths). They
have been broken off from the surrounding (country) rock by the force
of the injection of the dyke and are "floating" in the magma. |
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