BCGS

Birmingham Building Stones Trails

 

Trail 3: Around the Shops continued

 

We will not yet enter the covered Bullring Mall, but we can pat the head of the bronze bull (see page 1) at the entrance before heading down St Martin’s Walk towards St Martin’s Square. Stop at the statue of Horatio Nelson overlooking the square.

14. St. Martin’s Walk
Note the granite paving on the way down St. Martin’s Walk. This is almost certainly of Chinese origin, as is much of the 21st century block paving which we will encounter on the remainder of this trail. (Chinese granites are discussed in more detail towards the end of the trail in the section ‘Outside New Street Station’).

It is also worth noting that St. Martin’s Walk crosses the NE/SW trending Birmingham Fault. This downthrows to the SE bringing softer Triassic (c.200-250Ma) mudstones and siltstones against the harder sandstones of the higher ground. The steep descent at this point reflects the underlying geology.

Overlooking St. Martin’s Square is the statue of Horatio Nelson standing beside the ‘Victory’. It is the work of Sir Richard Westmacott and it was completed in 1809, pre-dating the famous Nelson’s column in Trafalgar Square. The statue is made of bronze, and is mounted on a column of Portland Whitbed Stone. (Portland Stone is described in more detail in Part 2 of these building stones tours of Birmingham).

Go down the steps to the right of the Statue of Nelson to enter St. Martin’s Square.

15. St Martin in the Bull Ring

A church existed here at the time of Peter de Bermingham in the 12th Century although it was first recorded in 1263. It was the original parish church of Birmingham until 1715, when St. Philip’s Church (later the Cathedral) was consecrated and became the new parish church for Birmingham. A history of this Medieval church’s evolution into the Victorian building standing today is recorded by Foster (2007). The bulk of the modern church was completed in 1875 under the supervision of architect J. A. Chatwin. Post World War II restorations and additions were carried out between 1950 and 1960 by Philip and Anthony Chatwin. The church is built in Grinshill Stone, although Foster (2007) notes that the spire, largely untouched by Chatwin and encased by P. C. Hardwick in 1855 was built of an undifferentiated ‘grey-brown sandstone’. Grinshill Stone is one of the Lower Triassic sandstones of the English Midlands (c.230–260Ma). Typically, these stones are red, with quartz grains well-coated with haematite. However, unusually, Grinshill is a buff-coloured sandstone, derived from the Helsby Sandstone Formation of the Sherwood Sandstone Group. It is a cross-bedded arkosic sandstone, composed predominantly of quartz and feldspar and free of iron. It is quarried from Grinshill near Wem in Shropshire. Although used locally since at least the Medieval period, it was worked on an industrial scale from the 19th Century, with over 30 quarries in operation.

Slabs of Hauteville Limestone are used as paving in front of the church porch. This has a distinctive yellow to pink colour variation, enhanced by abundant bioturbation. Hauteville is a Lower Cretaceous limestone around 145Ma, quarried from the eponymous French village. As the name suggests, the quarries are located high in the French Jura mountains, which follow roughly the line of the French/Swiss border. It is quarried seasonally; the quarries are buried in snow in the winter months. Hauteville Stone is variably fossiliferous, and a few examples are seen here. The surfaces of these slabs are rather battered, but look for the large (10cm) long section through a helically coiled ammonoid, Turrilites costatus, right on the very edge of a slab, up against the paving stones of St Martin’s Square. The black stone immediately adjacent to the Hauteville is the pyroxene–phyric, Cretaceous basalt (c.130-160Ma) from Fuding in Fujian province, SE China. It is marketed as Black Pearl (below).

Turn back to face St. Martin’s Walk, and enter the Lower Level of the Bullring shopping centre to the right of the steps.

16. Bullring
This area of Birmingham has been a market place since Peter de Bermingham bought a licence to trade in the 12th Century. Many of us who knew Birmingham in the later half of the 20th Century will remember the Bull Ring Centre well, a functional if not beautiful architectural conglomeration. Plans were in place by the late 1990s to redevelop this area and demolition and building works began in 2000 with the mall opening three years later, reincarnated as the one-word Bullring. The mall is designed by retail specialist architects Benoy Group. Foster (2007) remarks that the new complex is ‘retail architecture at an uncomfortable moment of transition’. Nevertheless, shopping malls are always good places to see decorative polished stone, and this makes the Bullring well worth a visit. The stone contract was carried out by engineers Chapman Taylor along with Stone Cladding International, a firm well-known for supplying particularly decorative, arguably ‘glitzy’ stones, many from exotic localities. The Mall is arranged on three levels which are continuous on the Lower Level but split into two ‘wings’ on the Middle and Upper Levels by St Martin’s Walk leading down to the church of St Martin’s. Paving stones, which vary in design and stone used from level to level, are the main use of decorative stones in the Bullring.

From the entrance, walk on to the junction with the main concourse (at Costa Coffee), looking at the decorative paving as you go (stop16a).

Cinza Rajado is named by Stone Cladding International as a stone used in the Mall. This marketing name is mainly used for a Brazilian marble but it is applied here to the yellow and black striped gneiss which is used for some areas of flooring, including the area between St. Martin’s Square entrance and the junction with the main concourse (at Costa Coffee). This is almost certainly derived from Brazil and almost certainly Archaean in age but its origin is unknown. ‘Rajado’ is Portuguese for ‘brindled’ and that is certainly a good description of this stone (NB. ‘cinza’ means grey).

Turn right onto the main concourse and head towards the roundel outside Selfridges. This is a good place to get your bearings and survey some of the main stone types used in the Bullring (stop 16b).

The main paving stone used throughout the complex is a yellow-coloured Spanish, mid-Cretaceous limestone (c.125Ma). This is generally marketed as Yana Limestone which is a corruption of one of the places of origin, La Jana near Tarragona in north-eastern Spain. It is worked on a large scale from the Aptian Benassal Formation. Texturally this unit is variable in both colour and fossil content. Colour ranges from yellow through cream and even pale pink and the stone is sometimes mottled with these colours. It is variably fossiliferous, with fossils – dominantly the oyster Toucasia sp. – concentrated in shell lags. Gastropods and ammonites are also present. Some slabs are entirely devoid of fossils, others are packed full with them.

Rosso Tigrato is another metamorphic rock, this time from Brazil. It has a tiger-striped appearance, due to being composed of a finely banded pink and black gneiss with narrow injections of granite which are rotated parallel to the foliation. This stone is used in decorative paving in the mall, notably here at the roundel (stop 16b). This stone is a migmatite, a ‘Juparana’ with a granitic composition; the pink colouration being imparted by potassic feldspars and biotite as the main mafic phase. It is from the Archaean São Francisco Craton, quarried near Ruy Barbosa in Bahia State. The São Francisco Craton (c.2.5–2.0Ga) is an ancient remnant of the Earth’s continental lithosphere covering a vast area near the NE coast of Brazil, about 1000 miles north of Rio de Janeiro).

This is a very popular stone, used for cladding buildings but also for paving both internally and externally. It is extractable in large slabs and blocks, due to the outcrop having a system of widely spaced joints. Vånga is also used for the cylindrical seats near the roundel (see photo above) and near the Lower Level exit from the Mall onto Smallbrook Queensway and the Bus Station outside Grand Central.

Retrace your steps along the concourse as far as the first flight of escalators (stop 16c).

These escalators are decoratively surrounded by Rosso Tigrato with a lozenge-shaped feature in Vånga granite between them. The escalator housing is faced with Yana Limestone, providing an opportunity to see some fossils without looking down.

Move on to the next flight of escalators, where two contrasting stones are used as paving and to face the escalator housing (stop 16d).

Vizag Blue is an attractive, dark purplish-coloured metamorphic rock. It is used around the escalators here, and for decorative features on the Upper Level of the Mall. It is a garnet-bearing migmatitic gneiss (c.1.5–2.0Ga) from the Eastern Ghats Mobile Belt of north east India. It is quarried in several localities around the towns of Srikakulam, Tekkali and Patapatnam in the state of Andra Pradesh. It is named after the local civic centre, Visakhapatnam, which is often shortened to ‘Vizag’.

Orissa Blue is the trade name of the accompanying stone. The Eastern Ghats Mobile Belt extends northwards through Andra Pradesh into Orissa (Odisha) State, parallel to the coast of the Bay of Bengal. Orissa Blue is paler in colour but essentially the same mineralogy (and age) as Vizag Blue. Texturally it is different and distinctive, with large, brick-shaped porphyroblasts of plagioclase aligned in the gneissose matrix. It too is very rich in red garnets.

The migmatites are part of a suite of very high grade metamorphic rocks of charnockitic composition, containing the minerals garnet, plagioclase and potassic feldspars, biotite, orthopyroxene and opalescent quartz. The Eastern Ghats Mobile Belt represents a series of deep crustal rocks accreted during multiple orogenic events during the Palaeoproterozoic, between 1.5 and 2 billion years ago. The pleasing colour of this stone and its ability to take a high polish has made it very popular as a decorative stone not only in shopping malls, but it has also become a stock material for monumental masons.

Note also the diamond-shaped paving feature near the bottom of the escalator. This makes attractive use of the two stones, contrasted against the Yana Limesstone.

Go up two flights of escalators to the Upper Mall. Turn round and head towards the end of the concourse.

The yellow fossiliferous Yana Limestone again forms the bulk of the paving, and there is continuity with the Lower Level design with further diamond-shaped features using Vizag Blue and Orissa Blue stone.

Exit the main concourse of the Bullring heading towards a conspicuous blue stained glass window. Follow this linkway round to emerge on the upper level of the Grand Central Mall.

Walk 3 continues on the next page…

 

 

References can be found on the last page of the walk (3.5).