A Photographers' Guide to the Geology of Northumberland

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Designed as a guide for landscape photographers who wish to photograph seascapes around Northumberland, UK.

Open Source Photographic Guide Project

These guides are created as part of a project I am working on…. to see more guides, please go to the UK – Northern England regional site - 
http://freephotoguidesuknortheng.blogspot.com/

Introduction

I guess many of of you might be thinking “what’s a geology guide got to do with photography”?  I think the best answer to that is another question – what is often the main feature included in landscape photographs?  If your landscape photographs are anything like mine then answer to that is ‘rocks’ and the colours/textures contained within those rocks.  I’m sure that for many people the fact that there is interest in the foreground with the colours and textures provided by the rocks is all the information they need.  However, I think it’s far more interesting to know how those rocks came into being in the first place.  It helps because it gives some context to the landscape and with that context comes a greater appreciation for the image about to be captured.

I hope that makes sense and I don’t just sound like some sort of reclusive rock-geek.  Either way, here’s the guide….

In The Beginning…

The earliest evidence of the formation of what we now call Northumberland can be found in the shales and sandstones close to the Scottish border.  These were formed some 450 million years ago when the area of Northumberland was located south of the equator under a deep ocean.  Plate tectonics (the process under which continents move around the Earth’s surface) caused the continental shelf on which Northumberland was situated to move northwards.  To the north of this shelf lay another continental shelf containing the area we now call Scotland.

 

The Creation of the Cheviots

About 400 million years ago, these two continental shelves collided.  This resulted in the formation of an enormous mountain range with volcanoes spewing great quantities of lava and ash, the evidence of which can be found at Bizzle and Hen Hole in the Cheviots. 

At the end of the volcanic activity any molten rock that did not reach the surface solidified as granite.  It is this granite which forms the Cheviot Hills that we see today.

 

The Sedimentary Rocks of the Carboniferous Period

Gradually, the area began to subside and by 350 million years ago Northumberland, still drifting north, was on the equator and beneath a shallow tropical sea.  This is the start of the Carboniferous period which left some of the most important (in terms of photographic interest) and thickest layers of geology in Northumberland.  

We know there was a warm tropical sea because of the evidence left in the rocks.  Coral reefs flourish in warm shallow waters, and when such reefs accumulate of millions years and form layers which subsequently get covered and crushed by subsequent layers of rocks they eventually form limestone.  Layers of exposed limestone can be seen at Beadnell and Cocklawburn Beach on the Northumberland coast; there is also a disused lime mine which can be found on Holy Island.  For those interested, fossils of corals and shells can be found in the limestone beds if you’re lucky. 

However, the limestones are only a small part of the large deposits made during the Carboniferous.  Also during this period, rivers, draining the land masses to the north, deposited vast quantities of silt and sand into the shallow sea.  The rocks that dominate much of Northumberland were formed at this time because of the vast amount of material deposited, creating very thick layers of shale and sandstone.  

Shale outcrops on Bamburgh Beach

The shales were formed by the compaction of fine silt beds which were likely to have been formed further out to sea, as silt, due its fine grain, travels further than sand.  You can identify shale by its very fine texturing, which, in the right light, can be shown off to great effect in photos (see above).  

Where shale has been subjected to intense heat it will often metamorphose into slate, and shale looks very much like slate, but is not as hard.  There is very little slate in Northumberland because the area has not been subjected to great heat and pressure since the Carboniferous.

Sandstone textures and colours at Seahouses

The sandstones were formed in the same way as the shales, but consist of larger-grained material.  The sandstones can erode into very interesting shapes, colours and textures depending on the minerals deposited at the time of their formation.  Seahouses beach has a great number of these interesting features, as have the rocks just below the Bath House at Howick

Sandstone textures below the Bath House at Howick

The rivers that flowed into the sea also created vast deltas, leaving even thicker deposits of sandstone.  These can be seen in The Fell Sandstone of the Simonside Hills and Shaftoe and Rothbury Crags.  

With the area being at the equator much of the delta surfaces were deeply forested.  This resulted in layer upon layer of compacted forest eventually forming coal seams which can be seen at outcrops south of Cullernose Point.

The Great Whin Sill 

Earth movements in the late Carboniferous period (290 million years ago) tilted the sandstone beds east and south.  These earth movements also stretched and cracked the beds, causing lines of weakness to form in the Earth’s crust.  Pressure from the Earth’s mantle forced magma through these faults.  The molten rocks never reached the surface but solidified in the cracks.  As they cooled they crystallised into dolerite.  Weathering has exposed areas of the dolerite to the surface and they are now collectively termed as The Great Whin Sill.  They underlie much of east and south Northumberland and extend south to the Pennines and County Durham.

Dolerite cliffs and rocks at Cullernose Point

Dolerite cliffs and rocks at Dunstanburgh

Outcrops of the Whin Sills have produced the most iconic landscape features of Northumberland.  The dolerite is much harder than the surrounding sandstones and shales, thereby allowing it to stand proud above the other rocks on the landscape.  The Sills form the Farne Islands and Holy Island; provide the base for Bamburgh Castle; Dunstanburgh Castle and Lindisfarne Priory, as well as forming the base of the dramatic central section of Hadrian’s Wall and the cliffs at Cullernose Point, south of Craster.

At Cullernose Point and Dunstanburgh Castle wave action against the cliffs has broken off sections of the dolerite which have been weathered into smooth boulders.  At both locations they make very attractive foreground interest. 

The Ice Age

After the creation of The Great Whin Sills, a relative quiet period followed for the next 285 million years – no other formations of significance took place, until 2.5 million years ago with the onset of the first Ice Age.  The vast areas of ice scraped away large areas of northern Northumberland leaving deposits of boulder clay in the south and east of the county.  

At the end of the last Ice Age the glaciers melted and sea levels rose, covering up much of the land to the east of Northumberland.  

The continued erosion of the sandstone and granite by Northumberland’s rivers feeds the North Sea with the material for Northumberland’s beautiful beaches which is the other principal land feature of note.

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