I have to go back to Yosemite; there’s just no denying it. I want to walk off into the woods, regardless of the bears, mountain lions, poison oak, rattlesnakes…

And I also have to go back for Mono Lake. I can’t believe that I was so close and didn’t go!

Mono Lake is an odd one, a freaky number. The white spires within the lake are tufa. It’s made of calcium carbonate, the same stuff as limestone. The process that forms tufa is essentially the same as cave formations (think stalagtites and flowstone), but not in a cave!

So you have some hard water and the calcium carbonate comes out of solution and becomes a solid, usually through a change in temperature, pressure or through turbulence of the water. This is exactly what happens at home when the kettle goes scaly.

For those interested in some chemistry, it’s this:

Ca(HCO3)2 <=> CaCO3 + H2O + CO2

Calcium bicarbonate to calcium carbonate plus water plus carbon dioxide

Even on the tufa scale, Mono Lake is pretty unusual. The columns have formed where springs enter the lake and they’ve only been exposed due to falling lake levels caused by water abstraction. They should be underwater!

I know A LOT about tufa; I studied it for 4 years. So you can probably understand why I’m upset about not going to Mono Lake and paddling between those white columns.

…don’t know when I’ll be back again. But it will happen, sometime.

I’ve just returned from a paddling trip to California. Although I didn’t have a burning desire to the visit the USA, I’ve now realised that those Americans have A LOT of space between their borders. The landscape is beautiful; the wilderness and the wildlife gave me a warm cosy feeling inside.

Sentinel Rock, elevation 7038ft

Although we didn’t paddle the Merced, we ‘allowed’ ourselves a day of tourism at Yosemite National Park. I admit that I’ve been lucky enough to travel to some pretty astounding places in my time, but Yosemite absolutely blew me away. I’ve never been anywhere remotely like it. The rocks literally tower from the ends of your toes! This was more than sufficient for me to ignore the multitudes of early season tourists that were crawling the surface of the ‘easy access’ parts of the park.

Yosemite is another bastion of our old friend, the granite. This spectacular landscape has formed over millions of years. The granite plutons cooled at depth and were gradually unroofed to the surface through processes of erosion. They rose to the heavens during the formation of the Sierra Nevada mountains and v-shaped valleys were eroded by the action of water. Glaciation has scoured the valleys further, grinding the rock and leaving hanging valleys high up within the peaks. A lake filled the valley and the sediments left behind have flattened the valley floor.

Today, the headwaters of the Merced river are continuing to modify the landscape. The granite appears striped by the trails of water running down it. Freeze-thaw action is levering off giant slabs of granite along the exfoliation joints. Yosemite continues to evolve.

Nevada Falls, 594ft

Exfoliation joints

Top of Nevada Falls, elevation 5910ft. Photo by Ol Renison.

Liberty Cap, elevation 7076ft. Photo by Ol Renison.

It's just a squirrel, man!

I came across this whilst looking for information on Mary Anning (1799 – 1847), a Lyme Regis fossil hunter who is, apparently, the cause of the infamous lines “she sells sea shells by the sea shore.”

The article discusses survey geologists Eileen Guppy and Eileen Hendriks. I was left quite stunned when I read this:

“both were unmarried as, officially, female survey officers had to resign on marriage up until 1975.”

In my world, 1975 doesn’t seem all that long ago. Being female and apparently finding pleasure in areas that society deem to be ‘male’ (science, geology, kayaking…get the picture?), I was horrified to discover that my life could have been very different if I had been born a few decades earlier. Or maybe I’m just naive.

Thankfully my world hasn’t been adversely affected by inequality. Well apart from my gripe about the lack of support for female academics who wish to have children. But this isn’t the place to go into that one!

These links made for further interesting reading…

Whitewater kayaking is my passion; the sea kayaking is a very pleasant sideline for when there isn’t any water in the rivers. I don’t tend to look at rocks too much when I’m on rivers, other than to note the rock type and smile at any pretties along the way. This is usually because I’m either:

1. Too terrified to care;
2. Travelling at high speed with a modicum of control;
3. Upside down/swimming and conversing with the fishies.

I was lucky enough to go to northern Portugal over New Year and was really stunned by the hospitality and beauty of this small corner of Europe.

The photo below shows Chris paddling the ‘Portage’ on the Paiva Gorge. This river reminded me a lot of Scotland in autumn, except that the trees lining the steep banks were Eucalyptus, Portugal’s cash crop.

Paiva Gorge, Portugal. Photo by Mark Rainsley.

The Paiva travels through a granite gorge where the rapids form as the water flows over and around large boulders. There were a couple of occasions were we had to get out and carry our boats around rapids that were too dangerous to run. I was surprised to note that both dodgy rapids were caused by a change in rock type, to meta-sediments. The heat from the granite has altered the sediments that it has intruded into. This is called contact metamorphism where the heat and pressure forms new minerals and changes the physical properties of the rocks that it influences, the so called  ’country rock’.

Contact metamorphism also resulted in my portaging a rapid, slipping and dropping my kayak on my foot. Ow! And it was only when I returned home that I realised I’d missed an opportunity to go and see the Giant Woodlice at Arouca.

Paiva Gorge, Portugal

And nothing to do with damaged sleeping apparatus.  If you visit the fossil forest, you only have to turn around to see these broken rocks.

Broken Beds, Lulworth Cove

The explanation board at the site blames the collapse of these once horizontal beds upon the dissolution of underlying salts. Rock Boy and I weren’t convinced by this explanation; the destruction just seemed too spectacular.

Further reading has since  informed me that this is an carbonate-evaporite breccia* formed by a hyper-saline lagoon** which contributed to the preservation of the trees. Gypsum (calcium sulphate) was deposited by evaporation of the lagoon but it has been altered chemically to calcium carbonate (what limestone is normally formed of). It is tectonic activity that has completely damaged these weak evaporite beds and folded some of the stronger limestone beds above.

Even the walls on the Isle of Purbeck are geologically themed.

* Breccia (pronounced brechia) means smashed up rock, of any type.

**Hyper-saline lagoons or seas are formed when a water body becomes enclosed and shallow. Evaporation of the water causes minerals to accumulate in the water and they eventually come out of solution as a solid. Think of the Dead Sea and salt pans.

The weather wasn’t so good for exploration out at sea. A pootle around Poole harbour followed by strong winds meant that any escape from the shelter of Lulworth Cove wasn’t going to be much fun. We therefore took the opportunity to explore the ‘Fossil Forest‘ just to the east of Lulworth Cove, along the cliffs. To be fair, it should really be called ‘Fossilised Absence of Forest‘, but that doesn’t really have the same (tree) ring to it. But they are still worth visiting if you have a spare moment.

'Fossil Forest', Lulworth Cove

These bulbous formations were created when rising water levels engulfed the trees and  stromatolites grew around the trunks. Stromatolites are formed when blue-green algae (cyanobacteria) trap and bind pieces of sediment. Over time, the layers of bacteria build upwards and outwards to form mounds. They are remarkably common in the fossil record, but a few living specimens can still be found today. In the case of the ‘Fossil Forest‘, the trees have decayed leaving distinctive mounds with hollow centres. They look a bit like giant rock doughnuts!

Windy seas beyond Lulworth Cove

If the paddle to and from Lundy wasn’t sufficient, we managed to summon up the energy to circumnavigate the island. It was well worth the effort…

Granite is characterised by its joints*. These are the cracks that run through the rock. They are formed initially during the cooling of the magma at depth, and then exacerbated by the relief of stresses during the exhumation process (literally the uplifting and unroofing the granite to the surface).

On Lundy the joints have been modified by the elements, particuarly by the sea. This has created a whole series of avenues and caves around the coast; a fantastic exploring ground. Or it would have been if our exploration hadn’t been curtailed by moans of seal pups. An eerie experience.

Exploring the Lundy coastline. Photo by Mark Rainsley.

*Not the same as exfoliation joints, whereby weathering causes the surface of the granite to peel off like layers of an onion.

After the dire summer last year we were finally blessed with a weekend of settled weather. It proved to be more than perfect for the 21 mile paddle from the North Devon coast to Lundy, and back.

Lundy is primarily formed of granite. Blah blah blah. Not that exciting you say? Well you’d be wrong!

Lundy mountains? Photo by Mark Rainsley.

Lundy granite was originally thought to be the synchronous with the other Devon and Cornwall granites, e.g. Dartmoor and Bodmin. It wasn’t until the development of dating techniques that it was discovered that Lundy granite is of Tertiary age (i.e. much much younger). This makes it part of the Tertiary Volcanic Province and related to the basalts in the Isles of Skye and Mull.

Apparently all caused by the separation of the British Isles from Greenland during the formation of the North Atlantic. Impressed yet?

Was the Granite Isle worth the 4.5 hrs it took to get there? Undoubtedly. The Lundy trip is still shrouded in the ‘halo’ that belongs to one of last year’s paddling highlights.

Granite Tors, Lundy. Photo by Mark Rainsley.

Dawn. Off the Exmoor coast.

This was the day that set all this rock m’larky in motion again.

I’d just got back from a week sea kayaking in Barra and I immediately jumped at the chance of a trip off the Purbeck coast. We set off from Kimmeridge Bay and (should I really admit this?) I was excited at the prospect of seeing the Kimmeridge Clay. I’d never seen it before, but knew that it was a Type Section*!

Portland Stone in the sun. Photo by Mark Rainsley.

The sun was shining and as we paddled east on our journey to Swanage, I got to traverse upwards through the geology of the Isle of Purbeck. As the rocks are sloping (dipping) to the east, younger and younger rocks appear in the cliffs as you paddle eastwards. Easy!

* Basically means that any exposure of the Kimmeridge Clay is called this, regardless of whether it’s located in Kimmeridge or not. Not every small village gets to name a rock.