Ben Nevis Caldera again

 I've posted about the Ben Nevis Caldera before but this sign outside the Ben Nevis Inn gives the best explanation I've seen. Granite is formed when magma solidifies underground over up to a million years. This gives the crystals time to grow. What seems to have happened here is that granite was forming in the underground magma chamber when the top of the volcano cone collapsed in. I've seen a caldera on Tenerife. It was huge and spectacular. Trying to imagine it in this ice ravaged landscape is difficult.

Wormholes in the Solway

We walked out on the mud at Bowness-on-Solway. There were a lot of wormholes. Einstein's vision of the Universe as a curved multi-dimensional surface of space-time leads to places where the surface curves back under itself. Then it is possible for "tunnels" to be opened up between the two different sections of space-time. These "tunnels" are called wormholes. If you were able to pop through a wormhole you'd immediately appear in another place at another time, I think. That's certainly the science fiction reading of it, but I was interested to see on the Wikipedia page https://en.wikipedia.org/wiki/Wormhole that wormholes arose as solutions to the Einstein field equations. Sounds like it is back to Roger Penrose's Road to Reality book to get myself a bit closer to those equations!

Poppies at Carlisle Castle

The installation of ceramic poppies that made such an impression 4 years ago at the Tower of London has been brought to Carlisle Castle this month. It is free to visit and is proving very popular. It is very thought-provoking. I was wondering about the way that the artist has modeled the curve from the top of the keep. From the outside I thought that it looked like a parabola. Careful measurement of the photograph shows that it goes out as far as it goes down so it is probably a section of a circle.

Pressure transducer and river levels in Carlisle

We found this by the river in Denton Holme. The pressure at the bottom of the river is measured using a pressure transducer. I looked up how one of these works https://www.omega.co.uk/prodinfo/pressure-transducers.html Strain gauges are essentially wires that get stretched, making the wire longer and thinner. Since resistance = resistivity x length/cross-sectional area, the resistance changes as the shape changes. A Wheatstone Bridge is an array of 3 known resistors along with an unknown from the strain gauge, from which the unknown resistance can be calculated. Pressure varies with depth. Pressure = depth x density x g. So if the resistance of the strain gauge is calibrated for different pressures, the depth of the water can be known from the resistance.

Sea level changes at Munlochy Bay

These graphics from Munlochy Bay on the Black Isle illustrate the sea level changes in Scotland that brought about the raised beaches on Islay.

Raised beach at Kintra on Islay

I found a lovely example of a raised beach at Oban recently and reminded of these that I found on Islay last year. The idea is that the weight of the ice over the land mass during the Ice Age pushed the continental crust down. When the ice melted, it has been rebounding ever since. I have read about the ice being high enough in places so that only the peaks of the mountains can peak out. That would suggest say a 1000m deep layer of ice. Ice has a density of 917 kg per cubic metre. That would mean a pressure of 917,000 Pascals underneath. That's almost 10 times atmospheric pressure. What bothers me is that there was time for the waves to cut a flat beach platform but that has been preserved instead of there being a gradual slope as the land moves up a few cm each year.

Bond energies at Inveraray

Looking at the supermarket trolley stack at Inveraray, it finally occurred to me that this is a good analogy for calculating bond energies in Chemistry. I teach that energy is needed to break bonds and that energy is given off when bonds are remade. So I put in money to break the chain and get a trolley but I get money back when I remake the bond between the trolleys. The view was better round the corner though...