That is a good question. This is the largest feature of this type that I have seen, but I'm not a sedimentologist. When you have more deeply buried sediments some water-rich beds can become liquified by seismic shaking and then intrude through the overlying strata (as the water content makes them less dense that ne overlying rock), just like igneous intrusions. This requires there to be some level of bonding in the sediments so that the overkying rocks behave in a brittle manner, meaning that they must be buruied suffieciently far for diagenesis to have started (probably several km depth). These are called Neptunian dykes and can be really large (extending over kilometre lengthscales) and can be important in the formation and geometry of oil and gas reservoirs.

Hi, yes the great slab is made of volcanic ash, just like all the other rocks on Bowfell and the crinkles. The convolute beds we see here show that the beds beds were deposited on a slope. It is quite common for volcanic ash to be deposited on sloping land - sides of volcanoes, or disrupted blocks in caldera floors. Within calderas, there is further rotation of the floor as blocks are broken up and subsided into the emptying magma chambers during large eruptions. There is also some tectonic folding of the rocks in later mountain building events, but this is minor within the Borrowdale Volcanics (which Langdale is part of) as they acted as a rigid block, concentrating the main deformation to their South along the shores of Coniston Water. so most of the tilting you see around Bowfell probably occurred as part of the eruptive process.

Absolutely!

If your compass does get demagnetised - Don't despair! It is possible to remagnetise it (with care) by stroking it with a bar magnet. Make sure you get the polarity the right way round!

Thank you so much!

Yes, water is so important. I don't think I have done anything on the other efferect it has beyond affecting metl properties (and hence eruptive styles) - but it also has a control on solid-state viscosity and hence convective styles. Many geologists think that without surface water there would be no plate tectonics. Probably a subject for a longer video sometime.

Thank you, glad you like it.

Glad you liked it!

That is a really good question. Normally these drusy pegmatites are formed by liquid immiscibility driven by thermodynamic equilibrium. In that case ther is a formal requirement for the minerals to have the same compositions. So only differences in size and amounts of the minerals are possible. BUT… there are other non-equilibrium ways to produce pegmatite - see the video coming out this Saturday. In that case composition doesn’t have to be the same and you can even grow different minerals. This is the sort of pegmatite where you can find the really exotic minerals.

It has been such good weather in the North West in mid-September it would have been a crime not to get out!

So glad you like them. Do spread the word!

Thank you! Glad you like them.

Hey Joe, good to hear from you. Granites are soooo complex. This is the first in three granite/crustal evolution vids where, hopefully the concepts and rocks will start to build into a coherent picture. But some of this is still being actively researched and our understanding will probably evolve over the coming years. It is great that Scotland's geology is still the source of new ideas and discoveries despite being one of the (if not the-) longest-studied regions in the world.

@@OneMinuteGeology yeah… I’m slowly getting my head around Granite and it’s igneous alter-ego Gabbro! It’s crazy that you can see mounts built with both of this right next to each other on the Isle of Skye… I think it was the Luib scenic look-out that you cans see the black gabbros right next to that red granite hilltops?

@@jncolligan1 yes, the granite-gabbro association is a striking one. Skye is a very good example of how large basic intrusions can heat the crust sufficiently to partially melt it, making granites. These are A-type granites, which are lower in water than the mountain-building S-type granites and so I expect will be less likely to contain pegmatites (not that I have looked hard for pegmatite in the Red Cuillin). You get A-type granites associated with mantle plumes interacting with continental crust - on Skye, associated with the Columbia River basalts and Yellowstone, to name a few. There is a great itinerary into Camasunary Bay where you can see how gabbro dykes have heated the Torridon sandstone sufficiently to melt it. Let’s do it sometime.

You didn't see me climbing!

@@OneMinuteGeology If that lot fell, you would be oozing, not climbing. It looks just like a deadfall trap.

I've been watching these from the USA for a couple of years. You have great geology over there. It's just that it rains all the time😂

Yes, there are loads of classic sites. The problem is we are normally on our way somewhere else.

@@mikelong9638 true, not quite always. But at least we don’t have rattlers.

@@OneMinuteGeology You had to mention that!

I do offer guided geology days in the UK. Are you UK based?

They are a type of slickenside (or in modern terminology fault-plane lineations - I prefer the old slickenside). There are two main types of FPL - aligned crystals and gouge-type FPLs. These are aligned crystals, which have the sense of roughness as described here. The gouge-type FPLs have the opposite sense of roughness (and since slickenside means 'polished surface' in the original German) they are possibly 'true slickensides'. So you have to be a little careful when determining fault kinemantics from these features. As always, it is a bit more complex....

Thank you, for today lesson.

Yes. Technical term meaning 'with hints of blue colour', as in 'bluey-grey'.

Hah, Great! I guess the seafloor is quite rugged off the Point - do Cod like nooks to hide in or are they more open water fish? I remember fishing with my uncle out of Carnoustie as a lad and one side of the boat being super abundant for a spell of half an hour or so, but the other side catching nothing. We assumed the line had found a crevice in the seafloor. But I don't remember what fish we caught.

Cheers, Glad you liked it!

Glad you like them.

Good afternoon from Japan, via China! Watch this space for a few non-UK vids in the coming months

The closure of the Iapetus ocean started around 450 Milion years and by 300 million the collision was pretty much over - but yes, that was the event which brought N America and Eurasia together as part of building the Pangea supercontinent.

yes they are - often at the surface.

the films of the cut cut together well. Hope you are all well as well.

Thanks Mike.

Ah yes, the Old Red Sandstone has plenty of iron in it.

Thanks for your concern. I was with the mine custodian so in very safe hands.

Yes indeed!

SO glad you liked it. Thanks.

😀😀😀 Hope you are enjoying the mountains!

Thank you so much. Glad you liked it.

Yes, While Skolithos is a generic term for vertical burrows which covers a wide range of geological time, I guess yours are similar age in rocks deformed by the Appalacian Orogeny? Glad you like the vids.

It took a bit of explaining but the cameraman got the idea in the end

These trace fossils aren’t great for dating rocks as they occur across a wide range of time. But in this case it is their very first appearance at the start of the Cambrian. Around 550 million years ago.