Saturday, 30 April 2022

The Museum of London

A Roman mosaic at the Museum of London

At the end of my exploration of the remains of the London Wall and the Roman fort in the north-west corner of the walled city of London, I headed off to find the entrance to the Museum of London  – a museum that I had never visited when living in London.
Pleistocene mammal fossils and stone tools

I was mindful that, although only 1:30 in the afternoon, I still had the church of St. Bartholomew the Great to visit and I soon realised that this museum would need a few hours to properly appreciate its various exhibits. Starting at the London before London displays, I just took a few photos of the Pleistocene mammal fossils and flint tools collected from the Lower Thames Valley before moving on to Roman London.
Sculptures of Roman soldiers

As I passed through the gallery, I encountered several large stone artefacts, including a 3rd century statue of a centurion - found during the rebuilding of St. Martin's church on Ludgate Hill in 1669  - and a 1st - 2nd century soldier, which was originally part of a tomb. The latter was recovered from a tower on the wall on Camomile street, where it had been recycled for use as a building material.
A  detail of the mosaic floor
I particularly liked the large section of a mosaic floor forms that forms the centrepiece of a reconstructed living room, but the display of artefacts from the Temple of Mithras - discovered in 1954 – are also very impressive.
Artefacts from the Temple of Mithras
These sculptures are thought to be made in Italy, using either native Italian marble or marble imported from Turkey but, not having the time to closely look at the stones used in any of the various artefacts that I saw, I will have to take a better look when I next visit.
Sculpture of four mother goddesses
I passed by several more large sculpted block and panels carved in relief, as well as very many others on a much smaller scale, without giving them the attention they really deserved and I continued into the Medieval London gallery.
Various Roman artefacts

The large stone artefacts are less numerous than those in the Roman London gallery, but there are are good examples of an early C11 century grave cover and grave marker in the Ringerike style, which was popular in Scandinavia and late Anglo-Saxon England.
A grave marker
From the later mediaeval period, there are several architectural details that were salvaged from the demolished porch to the Guildhall. These include sections of a large heraldic shield and the four statues of the Virtues dated c.1430 - Temperance, Fortitude, Justice and Prudence - which occupied niches alongside Christ, Moses and Aaron.
The Virtues
Architectural details, of all materials and sizes, form a substantial part of the Medieval London gallery exhibits, but I was by this time very conscious that I had to continue with the next stage of my walk and didn’t stop to look at them in any detail.
Various architectural details
This short account of the Museum of London certainly doesn’t do it justice, as I have only highlighted a few artefacts that I think would be of interest to readers of this Language of Stone Blog. On leaving the museum, I made a point of mentioning to the staff on the reception that I had thoroughly enjoyed my experience and would return at another time.
A statue of Saint Christopher

Thursday, 28 April 2022

An Exploration of London Wall

The London Wall at St. Alphage Garden

During my very brief investigation of the churchyard of St. Giles Cripplegate, I could hardly miss the remains of the London Wall – with the foundations of a bastion – that lie on the other side of a water feature to the immediate south of the church.
The wall and bastion to the south of St. Giles Cripplegate

This section originally formed the northern side of the Roman fort, built c AD 120 in Kentish Rag stone from Maidstone in Kent. In the C13, during the rebuilding of the wall, a series of towers were added and most of the surviving masonry dates to this period.
A section of the London Wall Walk
When preparing my walk, the best route along the London Wall that I found was produced by the Museum of London back in 1984 and, following the London Wall Walk, I retraced my steps back to St. Alphage Garden.
The wall at St. Alphage Garden

A good section is exposed here, with Roman remains excavated from beneath the current street level being succeeded by mediaeval repairs and an upper section in brick, with crenellations and diapers, was added in 1477.
A detail of the wall at St. Alphage Garden

I didn’t have a good look at the masonry, but the lowest Roman part of the wall is predominantly built out of Kentish Rag rubble stone, with occasional nodules of flint and red tile – bound together by a lime mortar containing gravel sized aggregate.
A flint nodule and mortar with very coarse aggregate

Several sites have long since disappeared and are marked by very informative and well made ceramic information panels, as at Cripplegate, but some of these have been removed and I therefore concentrated on taking photos rather than seeking out the panels.
An information panel at Cripplegate
Moving on to the remaining north tower of the West Gate of the Roman Fort, which is set next to the access road to an underground car park, the first impression is of a large brick structure, with a fragment of Kentish Rag walling attached to it. The tower was lined in brick when used as a warehouse in the C19, but its northern part still retains a good section of original rubble walling.
Views of the West Gate

The wall continues north until it is interrupted by the Barber-Surgeons' Hall tower, where only the lower section of the rubble wall remains. There is not much to see here and I continued to the St. Giles Cripplegate tower, which marked the north-west corner of the London Wall, but has been reduced to two thirds of its original height.
Views of the St.Giles Cripplegate tower

The last section of the wall that I visited runs alongside Noble Street, with much of the remains appearing as footings that are barely visible amongst the wildflowers, which have been planted in the Noble Street Garden.
The remains of footings in Noble Street Garden

Although this is the least impressive part of the wall, with some sections retaining unsightly brickwork left from demolished C19 buildings, there are still substantial stretches of rubble walling that include some Roman work. With my investigation of the London Wall completed, I made my way to the Museum of London.
A section of rubble walling in Noble Street Garden

Wednesday, 27 April 2022

The Church of St. Giles Cripplegate

At the Church of St. Giles Cripplegate

When planning my day out in the City of London, with my principal objective being to explore the London Wall, one of the places that I wanted to see was the church of St. Giles Cripplegate, which is one of the city's few remaining mediaeval churches.
The church of St. Giles Cripplegate
The Norman church of 1090 was built on the site of a Saxon church, about which very little is known, and the Historic England description of its construction history is surprisingly very sparse. According to the church website, although it escaped the Great Fire of London, it has been rebuilt in 1394, again in 1545 and 1897 after fires and was then damaged twice during the Blitz.
A general view of the north elevation

Interestingly, the rebuilding of the church by Godfrey Allen after the 1897 fire was based on the architectural drawings for the 1545 restoration, which were kept in Lambeth Palace. Although this Perpendicular Gothic styling reproduces the mediaeval detailing, the choice of Portland stone for the north aisle and clerestory, to my eye, clashes with the Kentish Rag seen in the east wall of the chancel and the tower.
The tower
In South Yorkshire, the underlying Carboniferous and Permian strata have been supplying stone to build churches of a similar age and to restore and rebuild them ever since. Their main archaeological interest is in the styles of masonry that have evolved over the years, from rubble to roughly squared and coursed and then fine ashlar walling, and it is not often that you see such sudden changes in the building materials used over the ages.
The C17 brick extension to the tower
The late C17 alterations to the tower in red brick further add to the clash of materials, but this highlights the fact that London is set on soft Tertiary rocks, which are unable to provide building stone and it relies solely on imported materials  – with the costs of quarrying and changes in fashion often influencing the material used.
Kentish rag used in the south elevation

Moving round to the south elevation, I was surprised to see the aisle and clerestory are built in Kentish Rag but, as with all of the historic buildings that I had encountered since starting my walk from Mansion House underground station, I didn’t closely look at it closely.
A view east along the nave
The church was closed to the general public but, taking advantage of a rehearsal that was being set up for a performance in the evening, I was able to have a very quick look at its interior and take a general set of photographs, which record its principal architectural features.
A view of the arcades
I didn’t have the time to examine any of the stonework but, looking at my photographs, I would say that the arcades are built in limestone, which in London – certainly for exteriors – is usually Portland stone but I would have to examine it closely to determine this.
A view along the south aisle

Apart from the arcades, the only exposed masonry that I could see was in the south-east part of the chancel, where a piscina and a sedilia are set into walling that is made of Kentish Rag and possibly Reigate Stone. Again, I didn’t have the opportunity to study it closely but I am assuming that the massive dressed stonework is a limestone, which could be Caen stone from France.
The piscina and the sedilia
The sedilia has been partly obscured by the raising of the chancel floor, which is now laid with a chequerboard pattern comprising white Carrara marble from Italy and black polished Carboniferous limestone, which is probably from Belgium.
A view along the nave from the chancel

Various statues and monuments are scattered around the church, with perhaps the most notable memorial being that to Sir Martin Frobisher, who is probably best known for his efforts to find the Northwest Passage and his part in the defeat of the Spanish Armada in 1588.

The memorial to Sir Martin Frobisher

I finished my very brief investigation of the church by having a quick look at the former churchyard, which has been absorbed into the surrounding Barbican Estate and now only has a square monument and half a dozen plain stone coffins as reminder of its former function.
Stone coffins in the old churchyard

Monday, 18 April 2022

Urban Geology - Kentish Rag and Flint

The remains of the tower of the church of St. Alphege

When working in the building restoration industry in London, many years ago, I applied my degree in geology to the problem of stone identification and matching – to try and satisfy an architect's or a building surveyor's specification that would typically state: “All materials used for repairs shall match the existing as closely as possible”.

Various reference books used for stone matching

With no formal training in this specialist field and in the days before the internet, I would rely on the Natural Stone Directory, various Building Research Establishment reports and other publications such as the Stones and Marbles of Wallonia, which I was given by Dr. Eric Groessens during a visit to Interbuild trade exhibition in Birmingham.

London - Illustrated Geological Walks

Through practical experience, I soon learned the main types of stone that were used in the older buildings that I was working with; however, the two “London Illustrated Geological Walks” by Dr. Eric Robinson, sparked my interest in Urban Geology - with his work being continued by Dr. Ruth Siddall and the London Pavement Project and inspiring many others.

A publication inspired by Dr. Eric Robinson

During my day out in the City of London, in June 2021, although my principal objective was to explore the London Wall, I couldn’t help noticing all kinds of stones; however, having explored the mediaeval churches in and around South Yorkshire in recent years, I was more interested in the traditional materials used in London’s buildings than the ubiquitous imported granites.

The Guildhall
Leaving Guildhall Art Gallery, I had a quick look at the Guildhall, the administrative offices of the City of London that date back to 1440. The original building is constructed in Kentish Rag, a siliceous limestone of Cretaceous age, which was first shipped to London by the Romans from Maidstone in Kent. It was subsequently used for the mediaeval buildings, along with Reigate Stone, until Portland limestone became the dominant building stone during the C17.
A detail of Kentish Rag masonry at the Guildhall

With still so much planned to see in the day, I didn’t explore this wonderful building and made my way back to Gresham Street and then to Basinghall Street, where I encountered the former Guildhall Library and Museum. Built in 1872 to a Gothic Revival style design by Sir Horace Jones, it again uses rock faced Kentish Rag for the walling, with Bath Stone for the dressings.
The former Guildhall Library and Museum

Kentish Rag varies from very drab grey/green to grey/blue and, although a durable stone, it is very hard and intractable and incapable of being carved and I was therefore more interested in the wonderful grotesques carved in the Bath Stone.

Kentish Rag walling with grotesques carved in Bath Stone

When researching the locations of the remaining sections of the London Wall, in the time available I realised that it would be best to concentrate on the north-west part of the old walled city and, on Google Map, I was very curious about the fragment of a very old historic building that is sited just next to the road named London Wall.

The remains of the tower of the church of St. Alphege

This is the remains of the mediaeval central tower of the former church of St. Alphege, dating to the C14. It is an ancient church that was built directly on London Wall and which has a long construction history, on both sides of the wall. This includes some damage during the Great Fire of London, rebuilding in 1777, further damage during WWI and demolition in 1923 – leaving only the tower, which was gutted by fire during WWII
The remains of the tower of the church of St. Alphege
Bernard C. Worssam and Tim Tatton-Brown suggest that the assumption of Kentish Rag being suitable only for rubble walling, which I have generally adhered to, is not in fact correct. Living in the north of England, I haven't studied Kentish Rag or Reigate Stone but, nonetheless, if I examined them with the geologists' basic tools - a hand lens, a steel knife and hydrochloric acid - I think that I could readily distinguish them.
A detail of dressings to the flint walling
The dressings to the flint walling have been worked and shaped to a degree that I would not have expected, based on my experience of seeing many Kentish Rag churches in south London, where Bath Stone has been used for quoins, window surrounds etc; however, looking at the lamination of the dressings on my photos, I suspect that these could actually be Reigate Stone.

A view of the Charterhouse from Charterhouse Square

Continuing my walk, after discovering further examples of Kentish Rag in the London Wall and flint at the church of St. Bartholomew the Great, which I will describe in detail in the near future, I unexpectedly encountered the Charterhouse, which lies just outside the City of London in the London Borough of Islington.

The entrance coutryard at the Charterhouse

It was now 4 o’clock in the afternoon and, having been on the move for nearly 6 hours without a break, this complex of buildings looks like it needs a dedicated visit in its own right and I just took a few photographs of the parts that I could see.

Various building materials at the Charterhouse
A mixture of materials can be seen in various phases of building and I was interested to see a further use of knapped flint, in a chequerboard pattern thyat decorates a boundary wall. I had seen a lot of flint buildings in the Chalk regions around the Weald in south-east England, when visiting English Heritage properties while living in London but, as a professional geologist, I have never investigated its use as a building material. 
A boundary wall with a chequerboard pattern of knapped flint