Learning new geological terms at Scalloway

 

The BGS viewer names the rocks I found down the west side of Scalloway harbour, near the UHI, as being "granofelsic psammite". Turns out that psammite is the name for a generic metamorphosed sandstone and that granofelsic refers to its form or texture. It means it has grains visible to the naked eye that are fairly uniform. Now I thought I'd found a schist because it was quite shiny!

Burnt mounds on Shetland

The wonderful museum at Tangwick had an explanation for the many burnt mounds I kept seeing on maps. Apparently they date from the age before the existence of metal pans. I have seen Ray Mears in Canada use this technique to heat water in pre-metal birch bark pots that would burn up in a fire. Rocks are heated up in a fire and then placed in the water. The thermal energy from the rocks transfers to the water, raising the temperature of the water until the two reach thermal equilibrium. Repeated application of this technique broke the rocks and the broken bits were piled up - a burnt mound. I decided to try some data. Rock has a density of about 3 grams per cubic cm. A 10cm cube of rock would thus have a mass of 3kg. Granite has a specific heat capacity of about 800 J/kgK. A fire could heat the rock up to 500oC. Say that 5 litres of water, with a mass of 5kg, started at 10oC. Give thermal equilibrium as temperature T. Then 5 x 4200 x (T-10) = 3 x 800 x (500-T). I get T as 60 oC which sounds about right.

Uniform field : Tarmac's grave in Moffat

We visited McAdam's grave in Moffat. The crest had 3 arrows pointing downwards. Parallel arrows in a vector field show uniform field strength. This might be appropriate for his smooth road surfaces. 

Carbon storage on Shetland

 

This article says that liquid CO2 can be stored there before being sent down a pipeline to old oil fields to be sent underground.

Cyclopentane refrigerant

I saw this on the back of a fridge.

It turns out that cyclopentane has been used as a refrigerant to replace CFCs. It melts at -94oC. This is important because its temperature in the system will never be this low so it will not freeze in the pipes. Its boiling point is 49oC. The contents of the fridge don't heat it this high to turn it into a gas. Evaporation is achieved by compression and expansion to manage the pressure. The main reason for naming the refrigerant on the back must be that it is highly flammable if it escapes!

Looking for an igneous dyke at Galmisdale

 The BGS viewer showed a dyke below the camping pods at Eigg harbour. It is from the North Britain Palaeogene Dyke Suite - Basalt. I can't seem to find out much about it.

However, this rock on the side of the ridge of rock looks to have been baked. It is now very flaky. I'd say contact metamorphism.

And here are views of the ridge of rock I think is going to be the dyke.

Secret listening house on Bute

 There's a lone house in the distance down this road at Scalpsie Bay on Bute.

Here's what the interpretation board had to say about it.

This surveillance will be possible because each design of propellor will have slightly different types of movement and vibration. It is possible to identify the frequencies that make up a noisy complicated sound by the process of a Fourier transform to produce a spectrum showing the amplitudes of each component frequency. Each propellor will have its own distinctive spectrum. That's important because our own submarines go up and down past Bute too!

Vortex shedding in Hobgrumble Gill

 The amazing mackerel sky was reflecting from the still waters high up on Hobgrumble Gill in Swindale. But I was still able to pick out the circular lens-like distortions on the surface of the water. They were slowly rotating.

The also seemed to come in lines, slowly drifting downstream. Tracing the lines back led to the corner of a rock for each line. I wonder if it is some kind of vortex shedding but I would have thought it would need a much more turbulent and faster flow than on this languid calm evening. I have marked some of the eddies in red on the picture below.

4D vector field?

It was hard to photograph - there are a few white specks visible in the photograph - but this corner was full of dandelion seeds moving on the breeze. It showed that there were  variations in the breeze in terms of direction and strength in a very small area, variations that would be impossible to sense. The dandelion seeds were like a vector field detector, showing direction, strength and also evolution of the field over time.

Sundial slightly out at Castle Howard

Between 3 and 4 on the sundial, there are 4 sections marking the quarter hours and then these are subdivided into 3, marking out 5 minute intervals. Hence the sundial gives the time as 3:40 when the watch says 3:48. This is most likely just a slight misalignment when the sundial was fixed. One hour is worth 15 degrees so 8 minutes represents a 2 degree misalignment.

Mass and weight in York

It's a regular Physics teacher grumble about saying weight and giving an answer in kg. I wonder if here the safety warning is blunted because not that many people can give their mass in kg. It's like when I get faced with Americans giving theirs in pounds. I have no concept of how big that is though I should resolve to learn. Here it requires more than one person to know their mass in kg!!

Temporarily bleached by the light

It's hard to see on this photo but when I woke up my lovely coloured bunting looked white. It was an illusion, it turns out. There was no light source in the room, only the window, so I suppose it's a bit like sitting at the back of an eyeball. In these circumstances, light reflected from objects behind me would then hit the bunting before being reflected back into my eye to show me the colours. This would mean the intensity of this coloured reflected light would be low. However, the white light from the pale cloudy sky was streaming through the holes in the crochet with a much greater intensity. This must be what I saw and why the bunting looked convincingly white.

Concretions in Valtos Sandstone, Laig Bay, Eigg

 I'd seen these amazing cannonballs trapped in the Jurassic sandstone on a YouTube film. Thanks to this brilliant article, I was able to find them very easily. Go down past the Catholic church to the north end of the beach and there they are!!

The article explains how the sand grains are cemented by calcite deposits seeping through. There is even more detail in this brilliant piece about how the change from aragonite to calcite caused the change. And the idea that each ball took millions of years to form is mind-blowing!

The gate post that plays a tune

 This gate post is on the path from Galmisdale to the caves on Eigg

We have found posts before that emit a note when the wind blows across the bolt hole in the middle. What was new this time was the top hole. Covering it with my hand gave a slightly different note. I should have paid more attention. I was thinking of it as being like a recorder and the fingering changes the length of the same mode stationary wave. But maybe here the trick is that it goes from being a stationary wave in a pipe with both ends open, so a half wavelength, to being a stationary wave in a pipe with one closed end, so a quarter of a wavelength. That would make a bigger difference in pitch.

Final chiller door claim

 

I've decided to tackle this one in a different way. Having got a ball park figure of 1 x 10^11J for the previous two claims, it should be the same here. 69 months is 5.75 years. 1 x 10^11 / 5.75 = 1.74 x 10^10 Joules per year. This is 48 million Joules per day. Now 1kWh = 3.6 million Joules. Hence this suggests the family home uses on average 13 kWh a day. Obviously houses will vary but the figure is not unrealistic.

Another claim about supermarket chiller doors

 

My TV is a small one and is rated at 50W. In Joules over 76 years, that is 76 x 365.25 x 24 x 60 x 60 x 50 = 1.2 x 10^11J. Having got 0.6 x 10^11 for the claim about a lighthouse, there's a 50% difference here. However, given the variation in power of a TV and presumably of a lighthouse, they are not bad in terms of ball park figure.

Robert Boyle and the Gaelic Bible

 

We went to see Rob Roy's grave it Balquidder. Apparently he's not actually buried there!! However, there are some wonderful displays in the church. One minister, Robert Kirk, was a Gaelic scholar who oversaw the production of the first Bible in Gaelic. I was amazed to discover that this was funded by Robert Boyle, of Boyle's Law fame. He was apparently also interested in Kirk's work on "second sight". This isn't odd for scientists of the time given Newton's work on alchemy. One of Kirk's big jobs was putting a Gaelic translation of the Old Testament into Roman letters. I was wondering why I couldn't read the sample in the box but this must be the old Irish script.