Cullernose Point EarthCache

An Earthcache on the Northumberland coast. There are many spectacular locations on Northumberland’s coastline, this is one of our favourites. On a stormy winter day it can be awesome as the waves crash in, in the summer you can escape the crowds flocking to Craster. There is a place to park on the road, for a few cars. There is a good path, sometimes muddy, to the final location. Only the last few metres involve a walk down a short slope.

From GZ you can see an outcrop of the Whin Sill to your left, forming the headland. This is made of dolerite, a hard igneous rock chemically similar to basalt but with larger crystals because it cooled more slowly. It was intruded as molten magma into the limestone during the Carboniferous geological period about 295 million years ago. As the magma cooled slowly underground, it contracted and large vertical joints formed (columnar jointing) in the rock. Sea birds use the horizontal ledges in the dolerite for nesting.

The dolerite is resistant to weathering and erosion, so stands ‘up’ in the landscape. The dolerite at Cullernose point is the same resistant rock that Dunstanburgh Castle, Bamburgh Castle, Lindisfarne Castle and parts of Hadrian’s Wall stand on.  If you look carefully, and the tide is out, you should be able to see a smaller dolerite dike intrusion on the wave cut platform to your right (see waypoint for a good spot to view this from). This appears as a ‘wall’ of dark grey dolerite standing proud of the surrounding limestone.

Immediately in front of you are folds in the limestone, both anticlines (the fold points upwards) and synclines (the fold points downwards). The limestone was formed on a tropical sea-bed at an equatorial latitude. The horizontal strata have been folded into ‘whale-back’ folds, so-called because the axes of the folds are tilted giving the appearance of a whale’s back.

If the tide is out you can explore the foreshore, but be careful of the slippery rocks and drops on the wave cut platform and beach. All of the questions can be answered standing at GZ.

To log this Earthcache, email us answers to these questions. Please do NOT include the answers in your log. Logs without an email will be deleted:

1 - Standing at GZ looking out to sea, look immediately to your left. Some holes have been drilled into the fold in the limestone in 4 places (see photo). How many holes are there in total?

2 - Both the limestone and the dolerite date from the Carboniferous geological period, but which is the younger rock?

3 - Look at the sediment on the beach to your left in front of the cliff. Describe its size, shape and suggest the rock type it is made of, and why this is.

4 - Which geological force was responsible for folding the limestone into anticlines and synclines?

5 - Optional: upload a photo of you / your GPSr at site (but please don’t give away any of the answers!)

We hope you enjoy visiting.