Thursday, February 13, 2014
Geology lesson in art sketches - drawing and painting synclines
My resident dinosaur Darwin is enjoying sitting under my new big painting Turned Lulworth, Turned. But he wondered if perhaps I should explain all those little lines I'm starting to include in the paintings. And why I'm using them - how they relate to the actual geology I'm seeing on the coastline.
This large painting is inspired by the folded rocks by Lulworth Cove in Dorset, on the southern English coast.
These rocks were literally folded into curves by forces of nature!
The folds you see in rocks can be extremely acute angles like these, or large gentle curves across a much larger landscape so that you barely see them unless a large section is exposed. Because of erosion and exposure by the coast often these features are prominent at the seaside because we can see so much of the rock bedding.
These curves in layers are called synclines and anticlines.
In plain English, layers are put down - sediment from wind, water flow, etc - in the landscape over time. So the newer layers sit on top of the older when they're first laid down.
Over time the land and rock could be subject to forces that press on the layers and warp them into curves - the rock is trying to fit in a smaller squished space so it has to fold and bend.
The curved part where the original layers are push down to make a "U" bend is called the syncline. Where it is pushed up to create an arch is called the anticline.
Now, why would you need different names? Surely you can see which is U or arch?
Well, that's where the Earth gets fun! See, over time the whole kit and kaboodle could be spun around, turned upside down, tilted...
So the names help when we have no idea which way up these layers originally were. The syncline will always have the youngest rocks on the inside curve, while the anticline will have the oldest rocks on the inside curve. So once a geologist has dated the rocks, they can tell which way up the layers originally must have been and how they've been moved as a group. Before the rocks are dated the curve is actually called a synform until the syncline and anticline can be identified.
Now my own silly way of remembering the difference was that I figured in a syncline all the youngsters were crowded in the middle causing havoc and being sinful. While the old rock folk were relaxed and spread out.
The folds at Dorset were actually created during the continental collisions going back when the Alps were being created. (the Alpine Orogeny)
You can also see in this photo why my painting St Oswald has vertical lines in it, to represent the fold at that specific location.
See the coast paintings tina-m.com