St Peter’s Square was once St Peter’s Fields . This sacred spot – where a church stood until 1907 – was subsequently chosen as the site for the city’s memorial to its dead of the Great War. The architect approached to design it was Sir Edwin Lutyens, the creator of the Cenotaph in Whitehall and many other noble, poignant memorials. The Manchester memorial unveiled in 1924 was a variation on the cenotaph theme, flanked by two obelisks and with one of Lutyens’ Great War Stones – an altar – in front. The precise location, on the axis of Mosley Street, was very carefully considered so that the cenotaph is also visible from the west down Peter Street and from the south-east along Oxford Road. A few years later, Vincent Harris carefully aligned the portico of his fine Central Library to face the war memorial.
The square is home to the Manchester Cenotaph, St Peter's Square Metrolink tram stop and incorporates the Peace Garden. In 1819, the area around the square was the site of the Peterloo Massacre, the brutal dispersal by cavalry of a radical meeting with a political agenda for parliamentary reform.
St Peter’s cross
Waypoint 1 N53 28.655 W002 14.630
The cross is constructed of Portland stone rising from a stepped base. The column is decorated with three angels holding shields on which are carved the keys of St. Peter.
This cross marks the site of St. Peter's church which stood at this location from 1794 to 1907. The cross was unveiled in September 1908 to mark the site of St. Peter's Church which demolished in the winter of 1906-7.
Manchester War Memorial
Waypoint 2 N53 28.720 W002 14.580
Manchester's war memorial is a cenotaph, flanked by twin obelisks, and a Stone of Remembrance, all in Portland stone on a raised coved platform. The memorial covers an area of approximately 93 feet (28 metres) by 53 feet (16 metres). The cenotaph is 42 feet (13 metres) high made from 160 long tons (160,000 kilograms) of Portland stone. The pylon is surmounted by a sculpture of an unknown soldier, partially covered by his greatcoat. The pylon rises from the base in diminishing stages, narrowing as it rises. Below the soldier, on the front and rear, are moulded swords and imperial crowns, and to the sides are Manchester's coat of arms surrounded by laurel wreaths. In 2014, Manchester City Council dismantled the memorial and reconstructed it at the opposite end of St Peter's Square next to Manchester Town Hall to make room for the expanded Metrolink tram network. The memorial is a grade II listed structure. In 2015, Historic England recognised Lutyens' war memorials as a national collection and all were listed, had their listing upgraded or their list entries expanded.
Manchester Central Library
Waypoint 3 N53 28.670 W002 14.650
Manchester Central Library is the headquarters of the city's library and information service in Manchester. Facing St Peter's Square, it was designed by E. Vincent Harris and constructed between 1930 and 1934. The form of the building, a columned portico attached to a rotunda domed structure, is loosely derived from the Pantheon, Rome. The library building is grade II listed.
Designed by architect Vincent Harris, the striking rotunda form of the library was inspired by the Pantheon in Rome. Like its 2nd-century model, the library is a round building fronted by a large two-storey portico which forms the main entrance on St Peter's Square, and is surrounded by five bays of Corinthian Columns. Around the second and third floors is a Tuscan Colonnade topped by a band of unrelieved Portland Stone.
The pitched leaded roof appears from street level to be a dome, but this is only a surrounding roof. The dome that can be seen from within the Great Hall lies within this roof, and cannot be seen from the ground.
Geology of St Peter’s Square
Portland Stone
The Portland Stone is a limestone. Limestones are mostly made of calcium carbonate. This sedimentary limestone has been quarried for thousands of years from the Isle of Portland in Dorset, for its ease of working and its striking grey/white colour.
From fossil evidence it can be seen that the rock was originally deposited in a warm sea water lagoon which was rich in dissolved Calcite, a mineral form of calcium carbonate. The purity of the Portland Stone also suggests that the sea was especially clear water, and the seabed would have been covered by an ever increasing layer of grey/white calcareous mud. In the same way that kettles in hard water areas (high levels of dissolved lime) furr up with limestone deposits, the mud on the seabed in Jurassic times would have built up around small impurities forming small balls of limestone called ooliths. In turn these ooliths would have been cemented together by more calcium carbonate forming solid limestone. A common fossil in the stone is Ostrea (oyster) This Portland Stone proved to be an easy to work and popular building stone. However as with all sedimentary rocks there are variations in quality, surface appearance, resistance to weathering by acid rain, and as a consequence variations in price! Directly above the Portland Stone, geologically, is a workable band of limestone called Portland Roach. This limestone is very resistant to erosion but at some time in the past acidic rainwater or seawater percolated through the rock dissolving the Aragonite/ Nacre (a variety of calcium carbonate known popularly as Mother of Pearl), of fossil shells creating fossil shaped holes in the stone known as casts. This detracts from its visual appeal in high profile buildings, but where the stone has been used for building purposes two of the more obvious fossils can be clearly identified. The two fossils Aptyxiella portlandica a Gastropod (snail) and Trigonia gibbosa a bivalve lamellibranch (mussel) were named by the quarrymen as Portland Screw and Osses' Ead respectively. The fossils can clearly be seen in the rock as it begins to erode. It is these fossils that you are here to see!
Slate
Slate is a fine-grained, clayey metamorphic rock that cleaves, or splits, readily into thin slabs having great tensile strength and durability; some other rocks that occur in thin beds are improperly called slate because they can be used for roofing and similar purposes. Slate was formed under low-grade metamorphic conditions—i.e., under relatively low temperature and pressure. The original material was a fine clay, sometimes with sand or volcanic dust, usually in the form of a sedimentary rock (e.g. a mudstone or shale). The parent rock may be only partially altered so that some of the original mineralogy and sedimentary bedding are preserved; the bedding of the sediment as originally laid down may be indicated by alternating bands, sometimes seen on the cleavage faces. Cleavage is a super-induced structure, the result of pressure acting on the rock at some time when it was deeply buried beneath the Earth’s surface. On this account, slates occur chiefly among older rocks, although some occur in regions in which comparatively recent rocks have been folded and compressed as a result of mountain-building movements. The direction of cleavage depends upon the direction of the stresses applied during metamorphism. Slates may be black, blue, purple, red, green, or grey. Dark slates usually owe their colour to carbonaceous material or to finely divided iron sulphide. Reddish and purple varieties owe their colour to the presence of hematite (iron oxide). The principal minerals in slate are mica (in small, irregular scales), chlorite (in flakes), and quartz (in lens-shaped grains).
Granite
Feldspar is by far the most abundant group of minerals in the earth's crust, forming about 60% of terrestrial rocks. Most deposits offer sodium feldspar as well as potassium feldspar and mixed feldspars. Feldspars are primarily used in industrial applications for their alumina and alkali content. The term feldspar encompasses a whole range of materials. Most of the products we use on a daily basis are made with feldspar: glass for drinking, glass for protection, fiberglass for insulation, the floor tiles and shower basins in our bathrooms, and the tableware from which we eat. Feldspar is part of our daily life.
Feldspar minerals are essential components in igneous, metamorphic and sedimentary rocks, to such an extent that the classification of a number of rocks is based upon feldspar content. The mineralogical composition of most feldspars can be expressed in terms of the ternary system Orthoclase (KAlSi3O8), Albite (NaAlSi3O8) and Anorthite (CaAl2Si2O8).
Chemically, the feldspars are silicates of aluminium, containing sodium, potassium, iron, calcium, or barium or combinations of these elements.
The minerals of which the composition is comprised between Albite and Anorthite are known as the plagioclase feldspars, while those comprised between Albite and Orthoclase are called the alkali feldspars due to the presence of alkali metals sodium and potassium. The alkali feldspars are of particular interest in terms of industrial use of feldspars. Amongst the numerous rocks in which they are present, feldspars are particularly abundant in igneous rocks like granite, which contains up to 50% or 70% of alkaline feldspar.
You will normally find feldspar like this in a stone, and not as a larger-sized mineral, so here is what you will be looking for at the stone at GZ (example photo below was not taken at GZ):
Logging your Find
In order to log your find, please send a message to my profile answering the below questions, research maybe required.
In addition to the below questions, optionally upload a picture of yourself or your GPS with the largest fossil you can find. You can log your find immediately, but please send the answers within 24 hours. I will respond to your email as soon as I can. Logs where incomplete answers have been given, or where an email has not been received, may be deleted.
Questions
Cross (Waypoint 1)
1. Why do you think this stone was chosen for the cross?
2. Look around the cross. Are any of the faces weathered more than any others? Explain why you think this is.
War memorial (Waypoint 2)
3. Describe how the stone looks and feels.
4. Look at the fossil fragments that have been revealed as the stone erodes. What type of creatures do you think these are?
5. Estimate the size of the largest fossil that you can find
6. What does the habitat of the creatures tell you about how and where the stone was formed?
7. Erosion. Look at the two obelisks and explain why there are differences in the surface.
8. As you walk around the memorial you will see square slate plaques dedicated to the men and women of Manchester who have given their lives in the Korean war and conflicts since 1945. What gives the slate plaques their colour.
9. How do you explain the presence of different colours in the slate?
10. How many slate plaques are there?
11. Look at the memorial plaques on the ground. Who served in the Duke of Wellington’s west riding regiment and on what date?
Central Library building (Waypoint 3)
12. The coordinates have lead you to the front of Manchester Central Library. Have a look around the plinths below the main columns at the front of the building. How can you easily identify the Feldspar? Also describe the feldspar at GZ with its shape and colour.
13. How much percentage of the feldspar would you say the stone contains?
14. What average size are the reddish pink colored spots that you find? Based on your answer would you say that the rock cooled quickly or slowly?
15. As an optional extra please post photos of yourself in front of the cross, memorial or library
Please do not include any answers in your photos or logs.