Swimming pools are not really the best place to appreciate an earthquake. I was enjoying the benefits of Iceland’s geothermal heat in an open-air swimming pool on the only occasion I have been somewhere when an earthquake took place in that location, and I only discovered it had happened when I was told about it afterwards. Iceland, situated on a constructive plate margin, is tectonically active and earthquakes are not uncommon. They do, however, tend to be rather lower down on the Richter scale, in a way that might make it possible to appreciate an earthquake rather than being terrified by it.  Constructive plate margins are in tension and are located where the crust is already thin (particularly in oceanic crust) or where the crust is in the process of being thinned. In consequence it is possible for the tension to be released more incrementally (unlike compression where long periods of oh-so-quiet suddenly become oh-so-loud and very destructive). Not to say that incremental tension release doesn’t cause problems. The Icelandic attempts at harnessing geothermal energy from the very high heat flows encountered on the island have been severely hampered by the water circulation pipes being bent and broken by earth movement. Expensive and costly but not deadly. The earthquakes can however be a signal of something more deadly about to happen. An increase in earthquake activity is a sign that magma is on the move and therefore a helpful predictor of imminent volcanic eruption.

In contrast to Iceland’s constructive margin earthquake experience, that of a destructive plate margin is altogether more devastating. Destructive plate margins are so named because a slab of oceanic crust and lithospheric mantle (solid) are diving back down into the aesthenospheric mantle (fluid and deeper), dragging its trailing plate behind it. It could equally well be called a destructive plate margin for the naked violence of its volcanic eruptions and its earthquakes. Mount Tambora and Krakatoa in Indonesia, Mount Pele in Martinique, Nevada del Ruiz in Columbia and Santorini in Greece top the list for human casualties, and all are found on destructive plate margins. The same is true for the most devastating earthquakes. Tangshan and Sichaun in China, Haiti, Peru, Kashmir and the Indian Ocean earthquake centered just of the coast of Sumatra top the location-list of recent deadly earthquakes. With fatalities in the hundreds-of-thousands, earthquakes are more deadly than volcanoes. The cost is devastating in so many ways. Not only in terms of in human lives and injury, but also the misery caused by destruction of homes and businesses and infrastructure resulting in loss of income, famine and illness. There are several physical factors that dictate the scale of damage. The amount of energy released by the earthquake (its magnitude) is the principal measure of how much direct damage an earthquake may cause through shaking and ground rupture. Landslides, lahars (mud flows), flooding and liquefaction of soils and unconsolidated sediments are also direct consequences of earthquakes. Additionally, earthquakes may cause tsunamis. I vividly recollect the news and images from Indonesia and Japan on Boxing Day of 2004 showing the astonishing devastation caused by this earthquake-induced tsunami and the consequent tragedies that followed.

It may seem from this that Earthquakes are literally the great levellers, indiscriminate in who and what gets destroyed. As individuals and societies, we do however have knowledge and experience both of where earthquakes are likely to happen and what can be done to mitigate the consequences when an earthquake hits. There are two places I have visited which illustrate this well. The first is San Francisco. I’m not a great lover of any city, but San Francisco is one of my favourites, with its vibrant mix of peoples and its beautiful setting, wrapped around by San Francisco Bay and the Pacific Ocean and its many hills providing beautiful vistas. It is however a city in peril, located as it is on the San Andreas fault, a 1200km-long active transform-fault. The southwestern part of San Francisco is moving north, and the northeastern part is moving south: intermittently and violently. After the devastating 1906 earthquake in San Francisco, much work was done to make buildings and infrastructure more resilient to earthquakes, with good effect. These words from the bible come to mind:

“Therefore whoever hears these sayings of Mine, and does them, I will liken him to a wise man who built his house on the rock: and the rain descended, the floods came, and the winds blew and beat on that house; and it did not fall, for it was founded on the rock.

“But everyone who hears these sayings of Mine, and does not do them, will be like a foolish man who built his house on the sand: and the rain descended, the floods came, and the winds blew and beat on that house; and it fell. And great was its fall.” (Matthew 7:24-27)

However, wise government and judicious engineering is not enough. The central, hilly part of San Francisco is indeed founded on rock, a good place to build not only for rain, but also for earthquakes which have less effect on rock. In contrast the estuarine deposits which fringe the bay area and recent alluvial deposits (sand!) are susceptible to liquification during an earthquake, indeed causing much greater damage. The choices to build and live in these areas are not so much about wisdom versus foolishness as economic necessity. The suburbs built on these soft deposits tend to be the poorest areas in the city. If your house is more likely to be destroyed by an earthquake in an area where earthquakes are inevitable, insurance becomes more expensive and the value of your real estate drops.

In contrast to San Francisco (wealthy albeit with a significant underclass within one of the wealthiest nations) Kathmandu is poor. Nepal is the second poorest nation in Asia. This fact can be attributed to political instability and corruption. I stayed in the Kathmandu valley when I visited Nepal in 2011. We stayed in a lodging house delightfully located in the centre of Bhaktapur. This wonderfully preserved ancient city with its temples and courtyards made of wood, stone, brick and metal is designated as a World Heritage Site.  4 years later, in April 2015, a massive earthquake struck, with an epicentre near to Gorkha to the NE of Kathmandu. The effect of this earthquake was amplified in Kathmandu, Patan and Bhaktapur as they are built on a basin of lake sediments. As distressing as the images were of these ancient temples reduced to rubble it only remains symbolic of what the Nepali people went through, with nearly 9000 killed and nearly 22,000 injured. Nabraj, who had been my guide when in Pokhara, had his family home near to Gorkha. Mercifully his family all survived, but sadly his village was all but wiped out. With no insurance and no government help, rebuilding was a major challenge, with his income from tourism also reduced to rubble.

With so many confounding factors it is apparent that earthquakes scoring highest on the Richter Scale don’t necessarily bring the biggest death toll. Population density, poverty and politics have a strong influence too. These are large and seemingly intractable problems, however as a geologist I would suggest that one of the ways to help with this is to understand how earthquakes work so that engineering and socio-political solutions may be put in place.

This takes us, via a few thousand miles and through 340 million years of history to mystery rock number 17 for the Hadrian’s Wall Community Archaeology Project. It is an example of fault gouge, the material which is produced when rocks fracture and move past each other. This fault is part of a fault complex to be found on the Northumberland coast at Howick and is likely to have formed as this Carboniferous sedimentary basin developed. Faults are responsible for earthquakes. On the Howick fault, there has been a total of about 40m of movement, compared to 3m of movement on the fault plane which created the Nepal earthquake. The fault plane at Howick is likely to be much smaller than that in Nepal, which means that each metre of movement on the Howick fault would have generated less energy than each metre on the Nepal fault.  Additionally, this total of 40m would have been made through many much smaller movements spread over many millions of years. Given that this fault developed under crustal tension it would have created relatively low energy earthquakes.

The early Carboniferous period (in which these rocks formed) would have been home to many creatures including some of the earliest amphibians. I like to think that, like me, these creatures may have failed to appreciate these earthquakes as I did in my geothermal swimming pool in Iceland.

Attributions

Hekla eruption, February 2000. Photo by: Iceland monitor/Rax

Village on the coast of Sumatra: U.S. Navy photo by Photographer’s Mate 2nd Class Philip A. McDaniel, Public domain, via Wikimedia Commons

@Northumbrianman

The post Earthquakes, levelling and gouging appeared first on WallCAP.

Pottery kilns are greedy for power, so in preparation for installing a large second-hand kiln, I had a three-phase supply installed. This required cutting through a concrete path to make a trench and, when the cable had been laid, remaking the concrete path. It was the first big concreting project I had ever done, so when I had finished it, I neatly wrote the names of the people who had helped make it, including my older son Craig, along with the date.  It maybe that in a few hundred million years a geologist, of a highly evolved rat species, will unearth this concrete patch and use it as evidence in a paper on the ritual behaviour of primitive hominids in relationship to concrete structures.

If that writing is preserved over the millennia, it will have become a fossil. A particular sort of fossil.

When I hear the word fossil, the immediate images that come to mind are of ammonites, crinoids, shepherd’s crowns, trilobites and corals. Dinosaurs come to mind too, massive bones, lines of vertebrae, teeth and horns. These are the remains of the actual creature, usually their hard parts and often with their skeletons or shells replaced by a different mineral. The soft parts of an animal are rarely preserved, requiring an exceptional combination of speed of burial and environmental chemistry. Without this the remains would be predated, physically broken up, decayed, oxidized or dissolved. When this intersection of favorable circumstance does happen, it results in fossils which are amazing and tell us so much more about the animals – for example the recent discoveries in China of feathers on a number of dinosaur fossils.

For most ancient creatures, the information we have about their cells, muscles, nerves, brains, hearing, seeing and so on can only be inferred from the hard parts to which they attach or within which they are contained.  We can measure skull cavity sizes to infer brain size, bone size and density along with muscle attachment points to work on musculature. We can also see the gas chambers and siphuncle of ammonites which tell us a bit about their flotation mechanism. We can also put these ammonites into a flume to see how water-dynamic their shapes are and infer something of how well adapted they are for moving.

All of these things are fascinating and help build a picture of what these animals were like and what they were capable of.  What they don’t tell us is what they actually did. If Hamlet had looked at Yorick’s skull without knowing him well, alas he would not have been able to say anything of his infinite jest.

For ancient creatures, there is however, another type of fossil which helps us understand more of what these animals actually did. These are trace fossils, and ichnology is an important branch of paleontology which not only tells us what animals did, but also provides another set of diagnostic information which helps us understand the environment in which they are preserved.

The most obvious of trace fossils are footprints and trackways. Some of these even make an appearance in Roman remains. Just like my writing in the drying cement, there are some tiles at an undisclosed site where the paw prints of a dog can be found. Whether this is a particular dog that likes the feel of clay, or a potter’s dog that the owner wanted immortalized or whether potteries were particularly dog-rich environments is not clear. It simply tells us that dogs were around and dipping their paws where they probably weren’t welcome!

Fossil footprints and trackways are not uncommon, with dinosaur footprints making news in recent years with discoveries in the Jurassic strata on the Isle of Skye as well as in the Cretaceous rocks of the Isle of Wight. More locally, tracks discovered by Maurice Tucker, have been found in the lower Carboniferous rocks at Howick on the Northumberland coast. These proved to be from an early amphibian, probably from the Temnospondyl group and are one of the oldest amphibian footprints ever found.

Not all trace fossils are so obvious or so glamorous. Many of them are simply burrows or feeding trails and unlike the footprints, it is often hard to work out what animal made them. This is in part because many burrowing animals only consist of soft parts, so that what they did in chewing their way through soft sediment is the only record of their existence. This reminds me of a lecture we had at college from Professor Jim Kennedy on early molluscan evolution and their development to manage the relative positions of mouth and anus in their simple guts. My recollection is that Jim said something along the lines of, “much of their evolutionary effort was directed at working out how not to crap on their own heads”. This seems like a hard almost futile existence, but evolution is nothing if not a long game!

The rocks of the Carboniferous Period in Northumberland and beyond have a rich variety of trace fossils preserved within its many kilometers of deltaic and marine limestones. This month’s mystery rock, number 16 in a series, is one of them. This particular gem comes from the geologically fabulous Cocklawburn Beach just south of Berwick upon Tweed. Until very recently I had thought that these beautiful three-dimensional patterns in these siltstones glorified in the name of Eione monilforme. However, in trying to discover what sort of creature made these remarkable traces, my learned colleagues pointed me towards a paper in which they have acquired the even more remarkable name of Neoeione monilforme. It is a shame that scrabble doesn’t allow proper names! As far as the animal is concerned, I quote from Dr Katie Strang’s reply (an expert on all things Carboniferous – particularly sharks) “It was originally thought to be made by a mollusc, but has now been attributed to a deposit-feeding endobenthic (ie a lived in sediment at the lowest level in a lake or the sea) worm-like animal, that actively back-filled its burrow, but…”. As with many things geological, there is clearly still room for speculation, debate and further observation…

…and maybe this is a fitting sentiment to end this piece. My concrete scribblings have lasted all of 10 years so far and maybe some of the pots that were made in the kiln will appear, at some distant point in the future, in a Raturnine archaeological trench as a definitive marker for the late Anthropocene.

Attributions

Iguanodon footprint along the foreshore at Compton Bay.from https://ukfossils.co.uk/2016/06/17/compton-bay/

Dinosaur footprint An Corran: from https://www.nature.scot/dinosaur-sites-skye-be-given-official-protection

Amphibian footprint from Howick: in David Scarboro and Maurice Tucker: “Amphibian footprints from the mid-Carboniferous of Northumberland, England: Sedimentological context, preservation and significance” Palaeogeography Palaeoclimatology Palaeoecology 113(2):335-34

@Northumbrianman

The post Who gives a fecal pellet? appeared first on WallCAP.

We meet by the car park in Cawfields Quarry.

Aim: This field excursion is the next opportunity to see what the rocks that were used to make Hadrian’s Wall look like in their original pre-Roman setting. It also provides an opportunity to explore the way in which quarrying has been carried out. Across much of the length of the Wall the rocks are obscured by glacial material, soil and buildings, particularly in the west, so one of the best places to explore the rocks besides the coast is in river cuttings and quarries. Here in Cawfields Quarry and in the river cutting and quarries running alongside the Haltwhistle Burn we can explore rocks from the Carboniferous period, as well as the Whin Sill, that underly the central part of the Wall between Brampton and Chollerford.

We will visit locations in the burn and Cawfields Quarry to introduce different rock types, how they vary and how they relate to each other. This will be used as a way of looking at the evidence for what it was like when the rocks were being laid down which will give a good starting place to help understand how to identify rocks on Hadrian’s Wall. Methods of reading the rocks will be introduced during the walk. Whilst this is not essential for rock recognition it is highly recommended as a way of getting to know the stones. We will also learn about how quarrying has been carried out.

In summary we will be:

• Exploring the geology and landscape

• Learning how to recognise and categorise rocks

• Learning how to read the landscape

• Learning how to use geological maps

Logistics: We start at Cawfields Quarry car park where we will gather at a distance. From here we will walk from towards Haltwhislte following the old trackway down the Hatlwhistle Burn visiting 3 to 4 locations along the burn which will be a mixture of stream sections and old quarries. We will stop for picnic lunch during the walk along the burn to allow plenty of time to explore the burn. We then return to Cawfields Quarry in the afternoon to explore the Whin Sill and the way that the Wall interacts with the landscape here, including taking a short walk up to Milecastle 42. We will be walking between 3 and 4 miles along trackway and roadway for the most part but will need to do some scrambling to look at the rock faces in the quarries along Haltwhistle Burn.

Click here to register for this event.

COVID information: COVID-19 is a serious illness which is readily transmitted between people. To minimise the risk of passing on this disease during geo-walks, a process has been put in place. Whilst this gives a structure to manage the risk of transmission, for it to succeed there is a need for us to take individual responsibility to make this work. This is nothing new and I imagine you will already be doing this when you go out for shopping and other activities where you will be meeting people outside your own household. The three things that I would like us to do are:

• to be aware,
• to be considerate, and:
• to communicate.

To be aware of others around you so that you can negotiate how to remain distant from them

To be considerate. This is a difficult time, and we know that some people are more vulnerable than others. This includes the way that we feel about the situation and it is important to be aware of and respect others’ feelings and needs as we proceed.

To communicate. Humans are good at working out where we are physically in relation to others, however, to get the distancing sorted, using your awareness and consideration to communicate and negotiate your way around the walk is vital. Smiling, “you-go-firsts” and “I’ll leave the gate for you” amongst other considerations will oil the wheels of how this works, as well as making the day out more enjoyable.

Participants will be asked to perform a self-assessment of their health on the day of the walk. If they feel generally unwell and especially if they find that they have any of the currently recognised symptoms of COVID19, they will be asked to self-exclude from the walk and to let the leader know that they will not be attending.

The currently recognised symptoms of COVID19 illness can be found here:

https://www.bbc.co.uk/news/health-51048366

If participants find that they develop symptoms within 10 days after the walk please can you get in touch directly so that we can work as required with the government Track and Trace process.

Volunteer information:

• No previous experience required just come along and have a great morning out exploring rocks.
• Please bring your own hand gel and mask if you wish to wear one.
• Sturdy footwear is essential ie walking boots preferable but wellingtons ok – trainers not acceptable.
• Please bring appropriate clothing. You will need waterproofs if it is raining.
• Volunteers will need transport to the start point.
• If you have a camera/phone please bring this with you so that you can record pictures of the rocks to remind yourself of what you have seen.
• Please bring your own water and picnic lunch.

The post Haltwhistle Fieldtrip appeared first on WallCAP.

We meet at the car park by Denton Burn library, which can be accessed from West Road (A186) going W towards the A1 and 100m or so before the Denton Hall turret.

The curtain wall at Denton provides one of the few opportunities to examine a section of the curtain wall in the vicinity of Newcastle. This is a relatively short distance from Holy Cross at Wallsend where we are running an SSD event on the 23rd August. This will allow for an immediate comparison of the stone used in the curtain wall and in the Church.

Geologically the Wall here lies on top of rocks within the Middle Pennine Coal Measures Formation in the Carboniferous Period in an area which is rich in sandstones. This section of the wall is also near to an outcrops of a dyke which forms part of the Palaeogene dyke swarm which emanated from the Isle of Mull.

Click here to register for this event.

COVID information: COVID-19 is a serious illness which is readily transmitted between people. To minimise the risk of passing on this disease during geo-walks, a process has been put in place. Whilst this gives a structure to manage the risk of transmission, for it to succeed there is a need for us to take individual responsibility to make this work. This is nothing new and I imagine you will already be doing this when you go out for shopping and other activities where you will be meeting people outside your own household. The three things that I would like us to do are:

• to be aware,
• to be considerate, and:
• to communicate.

To be aware of others around you so that you can negotiate how to remain distant from them

To be considerate. This is a difficult time, and we know that some people are more vulnerable than others. This includes the way that we feel about the situation and it is important to be aware of and respect others’ feelings and needs as we proceed.

To communicate. Humans are good at working out where we are physically in relation to others, however, to get the distancing sorted, using your awareness and consideration to communicate and negotiate your way around the walk is vital. Smiling, “you-go-firsts” and “I’ll leave the gate for you” amongst other considerations will oil the wheels of how this works, as well as making the day out more enjoyable.

Participants will be asked to perform a self-assessment of their health on the day of the walk. If they feel generally unwell and especially if they find that they have any of the currently recognised symptoms of COVID19, they will be asked to self-exclude from the walk and to let the leader know that they will not be attending.

The currently recognised symptoms of COVID19 illness can be found here:

https://www.bbc.co.uk/news/health-51048366

If participants find that they develop symptoms within 10 days after the walk please can you get in touch directly so that we can work as required with the government Track and Trace process.

Volunteer information:

• No previous experience required just come along and have a great day investigating Wall stone!
• Please bring your own hand gel and mask if you wish to wear one.
• Please bring appropriate clothing and wear appropriate sturdy footwear. You will need waterproofs if it is raining.
• Volunteers will need to arrange their own transport.
• Please bring your own water and picnic lunch.

The post Denton – Examining Wall Stone appeared first on WallCAP.

We meet at the edge of the Holy Cross ruins. There is parking nearby in a small car park for the Holy Cross Cemetery which is accessed from the corner of Deneholm and Valley Gardens

As the Historic England listing for Holy Cross notes:

“Holy Cross Church is a well-preserved example of a medieval parochial chapel. The church and its associated graveyard have not been disturbed and will preserve deposits pertaining to the construction and use of the monument…

…The monument includes the remains of Holy Cross Church, situated on the top of a spur, which is bounded to the north, west and south by a deep ravine through which the Wallsend Burn flows.” As with the western end of the wall there are not many visible remains of the Wall albeit for different reasons, the eastern end of the wall being urbanised and built over. This makes examination of buildings like Holy Cross, which may have reused Roman stone of particular interest.

Click here to register for this event.

COVID information: COVID-19 is a serious illness which is readily transmitted between people. To minimise the risk of passing on this disease during geo-walks, a process has been put in place. Whilst this gives a structure to manage the risk of transmission, for it to succeed there is a need for us to take individual responsibility to make this work. This is nothing new and I imagine you will already be doing this when you go out for shopping and other activities where you will be meeting people outside your own household. The three things that I would like us to do are:

• to be aware,
• to be considerate, and:
• to communicate.

To be aware of others around you so that you can negotiate how to remain distant from them

To be considerate. This is a difficult time, and we know that some people are more vulnerable than others. This includes the way that we feel about the situation and it is important to be aware of and respect others’ feelings and needs as we proceed.

To communicate. Humans are good at working out where we are physically in relation to others, however, to get the distancing sorted, using your awareness and consideration to communicate and negotiate your way around the walk is vital. Smiling, “you-go-firsts” and “I’ll leave the gate for you” amongst other considerations will oil the wheels of how this works, as well as making the day out more enjoyable.

Participants will be asked to perform a self-assessment of their health on the day of the walk. If they feel generally unwell and especially if they find that they have any of the currently recognised symptoms of COVID19, they will be asked to self-exclude from the walk and to let the leader know that they will not be attending.

The currently recognised symptoms of COVID19 illness can be found here:

https://www.bbc.co.uk/news/health-51048366

If participants find that they develop symptoms within 10 days after the walk please can you get in touch directly so that we can work as required with the government Track and Trace process.

Volunteer information:

• No previous experience required just come along and have a great day investigating Wall stone!
• Please bring your own hand gel and mask if you wish to wear one.
• Please bring appropriate clothing and wear appropriate sturdy footwear. You will need waterproofs if it is raining.
• Volunteers will need to arrange their own transport.
• Please bring your own water and picnic lunch.

The post Holy Cross Wallsend – Investigating Repurposed Stone appeared first on WallCAP.

We meet at outside St Andrew’s church main entrance. Please bring your own packed lunch. We will spend the morning introducing and examining the Pele Tower and the afternoon introducing and examining St Andrew’s.

There is street parking available in the vicinity of the church.

The recent HAR dig has added to our understanding of the large range of Roman building work associated with the Roman town of Corbridge. St Andrew’s Corbridge and the adjacent Pele tower both contain material which is either definitively Roman or strongly suggestive of being so. Examining the Wall’s stone here allows us to consider not only the greater variety of stone shaped for more specialized buildings and structures associated with a Roman town.

Click here to register for this event.

COVID information: COVID-19 is a serious illness which is readily transmitted between people. To minimise the risk of passing on this disease during geo-walks, a process has been put in place. Whilst this gives a structure to manage the risk of transmission, for it to succeed there is a need for us to take individual responsibility to make this work. This is nothing new and I imagine you will already be doing this when you go out for shopping and other activities where you will be meeting people outside your own household. The three things that I would like us to do are:

• to be aware,
• to be considerate, and:
• to communicate.

To be aware of others around you so that you can negotiate how to remain distant from them

To be considerate. This is a difficult time, and we know that some people are more vulnerable than others. This includes the way that we feel about the situation and it is important to be aware of and respect others’ feelings and needs as we proceed.

To communicate. Humans are good at working out where we are physically in relation to others, however, to get the distancing sorted, using your awareness and consideration to communicate and negotiate your way around the walk is vital. Smiling, “you-go-firsts” and “I’ll leave the gate for you” amongst other considerations will oil the wheels of how this works, as well as making the day out more enjoyable.

Participants will be asked to perform a self-assessment of their health on the day of the walk. If they feel generally unwell and especially if they find that they have any of the currently recognised symptoms of COVID19, they will be asked to self-exclude from the walk and to let the leader know that they will not be attending.

The currently recognised symptoms of COVID19 illness can be found here:

https://www.bbc.co.uk/news/health-51048366

If participants find that they develop symptoms within 10 days after the walk please can you get in touch directly so that we can work as required with the government Track and Trace process.

Volunteer information:

• No previous experience required just come along and have a great day investigating Wall stone!
• Please bring your own hand gel and mask if you wish to wear one.
• Please bring appropriate clothing and wear appropriate sturdy footwear. You will need waterproofs if it is raining.
• Volunteers will need to arrange their own transport.
• Please bring your own water and picnic lunch.

The post Corbridge – Investigating Repurposed Stone appeared first on WallCAP.

The curtain wall at Planetrees near to Heavenfield, provides an opportunity to examine a section of the curtain wall which is a short distance both from Chollerton Church and from Chesters Fort where we are running SSD events on the 8th and 15th July respectively. This will allow for an immediate comparison of the stone used in the curtain wall and the fort which will help diagnose stone reuse in the Church. This section of Wall contains a change from the earlier larger width Wall to the later, narrower Wall. It is also near to Heavenfield as well as several possible quarry locations (at Written Crag for example) which we hope to explore further, later in the project.

Geologically the Wall here lies on top of rocks within the Stainmore Formation in the Carboniferous Period in an area which is rich in sandstones. Nearby these sandstones have been heavily eroded by ice, leaving flat exposures of the sandstone with lines scoured into them by the ice. This section of the wall is also near to significant outcrops of limestone which have been extensively quarried, and a feeder dyke for the Whin Sill.

Click here to register for this event.

COVID information: COVID-19 is a serious illness which is readily transmitted between people. To minimise the risk of passing on this disease during geo-walks, a process has been put in place. Whilst this gives a structure to manage the risk of transmission, for it to succeed there is a need for us to take individual responsibility to make this work. This is nothing new and I imagine you will already be doing this when you go out for shopping and other activities where you will be meeting people outside your own household. The three things that I would like us to do are:

• to be aware,
• to be considerate, and:
• to communicate.

To be aware of others around you so that you can negotiate how to remain distant from them

To be considerate. This is a difficult time, and we know that some people are more vulnerable than others. This includes the way that we feel about the situation and it is important to be aware of and respect others’ feelings and needs as we proceed.

To communicate. Humans are good at working out where we are physically in relation to others, however, to get the distancing sorted, using your awareness and consideration to communicate and negotiate your way around the walk is vital. Smiling, “you-go-firsts” and “I’ll leave the gate for you” amongst other considerations will oil the wheels of how this works, as well as making the day out more enjoyable.

Participants will be asked to perform a self-assessment of their health on the day of the walk. If they feel generally unwell and especially if they find that they have any of the currently recognised symptoms of COVID19, they will be asked to self-exclude from the walk and to let the leader know that they will not be attending.

The currently recognised symptoms of COVID19 illness can be found here:

https://www.bbc.co.uk/news/health-51048366

If participants find that they develop symptoms within 10 days after the walk please can you get in touch directly so that we can work as required with the government Track and Trace process.

Volunteer information:

• No previous experience required just come along and have a great morning examining Wall stone!
• Please bring your own hand gel and mask if you wish to wear one.
• Please bring appropriate clothing and wear appropriate sturdy footwear. You will need waterproofs if it is raining.
• Volunteers will need to arrange their own transport.
• Please bring your own water and picnic lunch.

The post Planetrees – Examining Wall Stone appeared first on WallCAP.

It may be that my memory is not quite right, but I have a strong recollection of visiting Ghiradelli Square Factory in San Francisco and being fascinated by the massive stone rollers grinding the chocolate to produce the beautifully smooth finished product. It was nearly 40 years ago, but I also have a recollection of the way that the chocolate was formed into beautiful folds against the bar at the bottom of the roller. The inexorable movement of the roller pulled the base of the viscous chocolate onwards while the bar held the top of the delicious smoothness in place. The rollers I am sure about, the ripples might just be in my imagination. A chocolate sundae and a sun-soaked view out over San Francisco Bay to Alcatraz and the Golden Gate Bridge after the event does do things to soften the memory.

It is a slightly tenuous, albeit irresistible analogy to make to describe the process which formed this month’s Mystery Rock for the Hadrian’s Wall Community Archaeology project.  Chocolate clearly isn’t magma, but both magma and chocolate are viscous liquids when heated albeit the magma is rather hotter than the chocolate. Basaltic magma is liquid at temperatures over 1000C and flows rapidly, as can be seen from the spectacular images coming from the current eruption at the Geldingadaler volcano in Iceland. What can also be seen from this eruption is the way that this magma becomes stickier as it cools from bright yellow heat to red heat to black. If the magma is continuing to move and the crust of cooling magma is kept hot enough that the surface doesn’t cool so much that it becomes brittle, then, just like the Ghiradelli chocolate, the cooling sticky lava will be pulled into ripples and braids which have a texture much like a coil of rope. As the top of the curve in the coils points along the direction that the underlying magma is flowing, ancient examples of ropy lava give useful evidence about the volcano from which it was erupted.

Mystery Rock 15 doesn’t come from a volcano though. This image was taken just north of Bamburgh Castle at Harkess Rocks at an exposure on the top of the Whin Sill. The shape and form of the ropy braids is unmistakable and the curve in the braids tells us how the magma was flowing. This all occurred under the ground, though, away from the cooling air which formed the ropy braids at Geldingadalir and in many other basaltic volcanoes. How could this have happened? The clue is in the curved outline of this small section of the Whin Sill which has this ropy texture. This whole process is contained within a gas bubble like a little world inside a very hot “snow globe”. Volatiles are a common component of magmas and the formation of gas bubbles a regular occurrence as the pressure on the magma is released as it reaches the surface. What is unusual is that the volatiles have come out of solution within the Whin Sill under the ground. This tells us that either the intrusion of the sill was close to the surface and/or there was a pressure release caused by the magma pulsing forward as it wedged its way between the layers of Carboniferous sedimentary rock. It is not surprising that this rare phenomenon is recorded as a significant point of interest within the series of Geological Conservation Reviews carried out to record the best of British geological exposures.

Just a short blog this month as there is so much fieldwork to organize. Maybe just a little time to visit the Doddington Milk Bar and enjoy one of their excellent chocolate sundaes whilst taking in a view of the Cheviots.

Attributions & Links

Chocolate Grinding: By Sanjay Acharya – Own work by uploader. Picture taken at Ghirardelli Square, San Francisco, California USA, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=5178665

Alcatraz: By Centpacrr (talk) (Uploads) – Own work, CC BY-SA 3.0, https://en.wikipedia.org/w/index.php?curid=38140500

Ropy Lava: By Tari Noelani Mattox,[1] USGS geologist[2][3] – https://web.archive.org/web/20070102035046/http://volcanoes.usgs.gov/Products/Pglossary/pahoehoe_ropy.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=700082

Link to Geldingadalir ropy lava flow:

https://www.youtube.com/watch?v=aZenXClZn4U

@Northumbrianman

The post Old Rope appeared first on WallCAP.

Chesters Roman fort occupies a pleasant position on the west bank of the North Tyne, guarding a key route from the north to Hadrian’s Wall, and the Roman town of Corbridge only a few miles to the southeast. Excavations between 1850-1970 have revealed a number of interesting buildings in and around the fort, and Examining the Wall’s Stone here allows us to consider the great variety of stone shaped for the more specialized buildings and structures associated with forts.

This full day of activity will include:

• An introduction to the archaeology and geology of Chesters Roman Fort
• Examining the stone in the fort buildings
• Stone carving session with professional stone carver Natasha Smith

About the Stone Carving Sessions

There will be a series of workshops throughout the day with small groups where you will be using hammer and stone-carving chisels to work with raw blocks of stone to find out how to carve stone under Natasha’s expert guidance. Trying out what it feels like to carve and inscribe stone is not only hugely satisfying but will also put you inside that Roman world and give an insight into the very nature of the different types of stone and how the Romans worked with these raw materials to create the Wall. The tools we will be using are almost identical to those that the Romans would have used!

COVID information: COVID-19 is a serious illness which is readily transmitted between people. To minimise the risk of passing on this disease during geo-walks, a process has been put in place. Whilst this gives a structure to manage the risk of transmission, for it to succeed there is a need for us to take individual responsibility to make this work. This is nothing new and I imagine you will already be doing this when you go out for shopping and other activities where you will be meeting people outside your own household. The three things that I would like us to do are:

• to be aware,
• to be considerate, and:
• to communicate.

To be aware of others around you so that you can negotiate how to remain distant from them

To be considerate. This is a difficult time, and we know that some people are more vulnerable than others. This includes the way that we feel about the situation and it is important to be aware of and respect others’ feelings and needs as we proceed.

To communicate. Humans are good at working out where we are physically in relation to others, however, to get the distancing sorted, using your awareness and consideration to communicate and negotiate your way around the walk is vital. Smiling, “you-go-firsts” and “I’ll leave the gate for you” amongst other considerations will oil the wheels of how this works, as well as making the day out more enjoyable.

Participants will be asked to perform a self-assessment of their health on the day of the walk. If they feel generally unwell and especially if they find that they have any of the currently recognised symptoms of COVID19, they will be asked to self-exclude from the walk and to let the leader know that they will not be attending.

The currently recognised symptoms of COVID19 illness can be found here:

https://www.bbc.co.uk/news/health-51048366

If participants find that they develop symptoms within 10 days after the walk please can you get in touch directly so that we can work as required with the government Track and Trace process.

Volunteer information:

• No previous experience required just come along and have a great morning investigating Wall stone!
• Please bring your own hand gel and mask if you wish to wear one.
• Please bring appropriate clothing and wear appropriate sturdy footwear. You will need waterproofs if it is raining.
• Volunteers will need to arrange their own transport.
• Please bring your own water and picnic lunch.

Please make sure you’ve read all of the above event information before registering.

The post Chesters Roman Fort – Stone Carving & Examining the Wall’s Stone appeared first on WallCAP.

Lanercost Priory was founded between 1165 and 1174 to house Augustinian canons, and many of its buildings survive to impressive height. Here we will Investigate Repurposed Wall Stone among the buildings of the priory, which were constructed by drawing on the ruins of Hadrian’s Wall that ran across the priory’s estate in the Middle Ages.

COVID information: COVID-19 is a serious illness which is readily transmitted between people. To minimise the risk of passing on this disease during geo-walks, a process has been put in place. Whilst this gives a structure to manage the risk of transmission, for it to succeed there is a need for us to take individual responsibility to make this work. This is nothing new and I imagine you will already be doing this when you go out for shopping and other activities where you will be meeting people outside your own household. The three things that I would like us to do are:

• to be aware,
• to be considerate, and:
• to communicate.

To be aware of others around you so that you can negotiate how to remain distant from them

To be considerate. This is a difficult time, and we know that some people are more vulnerable than others. This includes the way that we feel about the situation and it is important to be aware of and respect others’ feelings and needs as we proceed.

To communicate. Humans are good at working out where we are physically in relation to others, however, to get the distancing sorted, using your awareness and consideration to communicate and negotiate your way around the walk is vital. Smiling, “you-go-firsts” and “I’ll leave the gate for you” amongst other considerations will oil the wheels of how this works, as well as making the day out more enjoyable.

Participants will be asked to perform a self-assessment of their health on the day of the walk. If they feel generally unwell and especially if they find that they have any of the currently recognised symptoms of COVID19, they will be asked to self-exclude from the walk and to let the leader know that they will not be attending.

The currently recognised symptoms of COVID19 illness can be found here:

https://www.bbc.co.uk/news/health-51048366

If participants find that they develop symptoms within 10 days after the walk please can you get in touch directly so that we can work as required with the government Track and Trace process.

Volunteer information:

• No previous experience required just come along and have a great morning investigating Wall stone!
• Please bring your own hand gel and mask if you wish to wear one.
• Please bring appropriate clothing and wear appropriate sturdy footwear. You will need waterproofs if it is raining.
• Volunteers will need to arrange their own transport.
• Please bring your own water and picnic lunch.

Please make sure you’ve read all of the above event information before registering.

The post Lanercost Priory – Investigating Repurposed Wall Stone appeared first on WallCAP.