Cardiff Urban EarthCache EarthCache

This EarthCache has been developed with the intention of introducing the Geocacher to the geology and some of the history (as it is written in the stones used) of Cardiff City centre. The area covered by this EarthCache is only a small part of the centre of Cardiff, but it has been selected to include a number of different major rock types from a number of different locations/countries.

Whilst this EarthCache has been set up with the support of the South Wales Geologists Association the accuracy of the content of the EarthCache description is the responsibility of the EarthCache owners. The South Wales Group of the Geologists Association, a registered charity, promotes Geology in South Wales through lectures, field meetings and publications. Membership is open to anyone with an interest in Geology. Click here to go to the South Wales Geologists Association Website. Use the 'back' button to return here if you click the link.

Traditionally the study of geology concentrated on examining hand specimens in the laboratory or visiting quarries and cliff exposures. These locations are often not available to the general public and are usually inaccessible to those in wheelchairs.

Some geologists seem to think that geology is in quarries, it is as if once the quarried products leave the site they are no longer geological! Yet the quarried products abound in towns and cities and are mostly ignored by geologists and the general public. It has been suggested that city geology walks are an ideal way of introducing beginners to the subject and require less organisation than traditional 'fieldwork'.

It is possible to find lots of 'exposures' of rock in the city. These are evident in civic buildings and churches, cemeteries and churchyards, statues, shop fronts, roads (especially the old cobbled variety) and pavements, roofs, garden walls and even rockery gardens. These can be used to study and teach geology in much the same way as we would if they were still in the quarry.

Whilst looking at the geology in a city it is also possible to study other related topics such as weathering and pollution. Some buildings have a date on them telling us when they were erected. This information can be use to study the weathering of the rock over a known time span. We can also study the effect of acid rain on carbonate rocks.

You do not need any special equipment to complete this EarthCache just, if it is raining, waterproof clothes or an umbrella, a notebook and a pen or pencil. A camera, magnifying glass or hand lens and a grain size scale or ruler would be useful but are not requirements. A compass (to help determine if weathering is worse on a particular side of buildings) would be useful.

Hammers, chisels, acid bottles, trowels, etc, are not necessary and are really not encouraged.

Please upload as many pictures as you want as long as they do not provide any of the answers to the questions associated with this or other nearby caches.

Whilst trying not to give any clues away, it may be useful for you to consider Multicache GCHJXW – Cardiff Pictorial, while completing this EarthCache.

The intention is that the features described in this EarthCache are fully accessible to all Geocachers (see the note against Questions 1 and 2 regarding wheelchair user access to the portico of the National Museum of Wales) at all times. However, because of events being held in Cardiff City centre, this may not be so. We have planned this EarthCache so that the restricted access to Gorsedd Gardens associated with the Winter Wonderland (which is set up in mid October and runs through to mid January) should not cause any problems.

Completing this EarthCache involves a walk of about 1 to 1 ½ kilometres (the exact distance depends on the closeness each feature is examined) from the National Museum of Wales to Queen Street, then to Cardiff Castle and back to the start point. This should take 1 – 1 ½ hours.

Where possible we have provided co-ordinates for the features described below. We have also given directions as GPS signals are not always reliable in city centres.

The questions in this EarthCache relate to the geological features described and visited whilst walking this EarthCache route. Take time at each geological feature visited to examine the colour, texture, grain size, etc, (depending on how close you can get) of the stone. Please visit the area and do not simply try to find the answers by Internet research. Try to answer all questions. However, please give your reasons should you not be able to answer any particular question. As this cache is in an urban environment it will be subject to continual development/change.

To ensure that you visit the site there is, in addition to the questions, one requirement to confirm that you visited the area (this is detailed in the LOGGING THE CACHE section below and at Location 9).

We have presented the questions and logging requirement within the cache description text and collected them together at the end to help Geocachers who want just a single question and answer sheet. However, you will need access to the full text of the cache description in order to answer them.

Portland Stone, a white limestone from Dorset is a sedimentary rock that was laid down in the sea 145 million years ago, and it is used for all of the buildings in the Civic Centre of Cardiff. One of the places where it can be examined at the front of the National Museum of Wales – Figure 1. Built between 1913 and 1927, the portico allows us to see the effects on the stone of nearly a hundred years’ exposure to wind, rain, and frost.

Compare the smooth back wall of the portico which is almost ‘as new’ with the two faces of the giant columns. The side facing the prevailing weather is rough to touch while the less exposed opposite side is comparatively smooth. The roughness comes from the lime shells of Jurassic oysters in the stone being more resistant to acid rain etching than the background limestone. In the back wall you will see the same oyster shells as dark marks within the creamy white stone. Sometimes, the two valves of the oyster can be seen together in cross section. Usually, the shells are separated by tides and currents and broken into small fragments, difficult to identify as original shells.

Portland Stone is also used for the plinth of the statue of David Lloyd George (by Michael Rizzello – 1960) facing the Museum.

The large slabs steps, of the National Museum of Wales, speckled grey and white and are a typical 300 million year old granite from Cornwall. Granites are a mosaic of rock-forming minerals which cooled from a hot melt deep within the earth’s crust. The white rectangular crystals were the first to form, leaving the other minerals to occupy the remaining space in the mosaic. The white crystals are feldspar; the grey background mineral quartz; and the black minerals are hornblende or black mica. On rough surfaces, it is possible to pick out a gleaming silver flake which is muscovite mica.

Question 1. Examine the columns at the entrance to the National Museum of Wales and determine the direction of the prevailing weather.

Question 2. Whilst examining the columns determine which column has the feature identified in Figure 2 and comment on what it probably is. (Note, count as number one the circular column on the far left as you face the entrance to the National Museum of Wales.)

Question 3. Whilst completing this EarthCache determine the location where Figure 3 was taken (it is the plinth of one of the statues referred to) and (by examining the colour, texture, grain size, etc) the type of stone.

The Gorsedd Circle, Figure 4, was first erected for the 1899 Cardiff Eisteddfod. The upright slabs are Radyr Stone, a red breccias crowded with angular chips of gray limestone derived from the southern edge of the Coalfield. It was deposited as an alluvial fan at the mouth of a valley in north Cardiff some 200 million years ago during the Triassic Period when South Wales was a hot desert, a place seasonally torn by torrential rains.

Image source ccy57 log dated 26 February 2010 for cache GC1T0A1 – Cardiff Rivers #4 Taff-Ely-Rhymney – City Hall.

This statue of Lord Ninian Edward Crichton Stuart (by William Goscombe John - 1919), Figure 5, a local MP who died in battle during World War I, stands on a plinth of pale grey Scottish granite from Kemnay Quarry in mid-Aberdeenshire.

Image source Von-Horst log dated 02 September 2009 for cache GC1T0A1 – Cardiff Rivers #4 Taff-Ely-Rhymney – City Hall

City Hall, Figure 6, built 1901-06 of Portland Stone, is a really baroque building modelled on the grand buildings of Vienna and Paris. Look at the figures (an example of which is shown in Figure 7) which cap the roof line, carved from large single blocks from the Dorset quarries. These demonstrate that Portland Stone is a material which sculptors and masons would choose for their most three-dimensional and extravagant carvings.

Image source Welsheprechaun 16 April 2009 from Wikipedia

The rising slope, as you come out of the underpass on your way to Location 5, is paved with grey-green Pennant Sandstone flagstones and rows of grey granite blocks, probably from Portugal. The Coal Measure origins of the flagstones are apparent in the faint rust-staining and by pellets of ironstone in some of the slabs. Coal Measures is a lithostratigraphical term for the coal-bearing part of the Upper Carboniferous System.

At the top of the slope, the lower part of the tower of One Kingsway exhibits one of the many exotic stones which now crop up in Cardiff buildings. This blue-grey polished granitic rock is from Finland. If you look closely, the contrast between the pale feldspars and the darker quartz crystals is striking. The dark blue hue is caused by the crushing of the crystals and the resulting internal reflection of light. This occurred when the granite was squeezed in a mountain building event around 1100 million years ago (in short it has been metamorphosed).

The statue Nereid (by Nathan David – 1996), Figure 8, outside One Kingsway is ringed by the same stone and that in turn by more Pennant Sandstone flagstones.

There are three kinds of paving slab as well as grey granite blocks in front of Capitol Tower (the tallest structure in Cardiff), Figure 9. One is pale grey Pennant Sandstone with black coaly plant fragments, which also form the building’s steps. The darker grey slabs are from Caithness. They were deposited in a great lake basin about 375 million years ago. Their deeply mottled and roughly pitted and ridged surfaces are due to the sediment drying out after deposition. The other pavings are cast concrete, and much inferior to the natural stones.

Image source Seth Whales 14 November 2007 from Wikipedia

Heading down The Friary, past the Hilton Hotel which is of Portland Stone, you will soon come upon more foreign rocks in the columns of Principality House, Figure 10, on the left. Look at the light and dark bands of columns. The shimmering blue stone in the polished drums is from Larvik in the Oslo Fjord, Norway and is not found anywhere else in the world. It is called larvikite, and it formed from molten rock. The paler drums are the same stone but unpolished. The shimmer (iridescence) is a property of large feldspar crystals which are shot through with tiny grains of metal ores which both deflect and absorb white light.

Principality Building, on the corner of The Friary and Queen Street, is deep yellow Bath Stone which can best be seen in the corner entrance. Here, the tiny rounded grains of lime which give the stone its character and its geological name ‘oolite’ (referring to the fish egg texture) can be seen, along with irregular veins of calcite which cross the surfaces – another recognition detail. The Jurassic seas were current swept, so all shells were broken into tiny fragments. The modern window surrounds are a strange mix of different materials including a yellow artificial paste. Also here, we find grey granite, and more larvikite (some of which is polished); other nearby bands are unpolished (riven or hammer-dressed).

The tall columns at Lloyds TSB Bank (at 31 Queen Street), Figure 11, are also of larvikite. Its dark grey tone tells us that this came from a high level in the quarries. More modern stone comes from deeper in the quarries and is lighter in colour. The deep red stone in the bank frontage is Graverfors or Vanevik Granite from mid-Sweden which was popular in Britain before World war I. Close to the entrance you will notice that it contains a deep blue quartz, deeper than that at One Kingsway, showing that this granite has also been involved in mountain building. The facade above street level is carved Portland Stone.

Logging Requirement. There is one logging requirement to confirm that you visited the area. This requirement should be completed at Location 9. There is a statue in the street opposite Lloyds TSB. The statue is called ‘Mother and Son’ (by Robert Thomas – 2005). Either: -

a. State what toy is in the Mother’s string bag?

or

b. Take a picture of your GPS next to this statue (without giving away the answer to the above question).

Whilst walking along Queen Street towards Location 10, which is at Cardiff Castle, you will pass a number of different stones used in the shop fronts.

On the south side of Queen Street west of The Friary is one of the most elaborate buildings on Queen Street (occupied by Gap at 24 – 26 Queen Street), Figure 12, which was built in Venetian Gothic style in 1878 by C E Bernard. Such decoration is probably the result of using the artificial stones which were popular at that time. When you look to the door surround, it is difficult to decide whether this is waxed and polished Portland Stone or really artificial. Geology experts also could not decide as to which it was.

What a contrast can be seen on the north side of Queen Street. Here the white slab-faced block opposite Gap (occupied by Little Waitrose and Burton’s) is a bland modern complex clad in Portland Stone.

Poundland and Laura Ashley, next door, have a grand classical 1920’s frontage with four fluted Portland Stone columns which look as though they should be in Cathays Park. The upper facade of Santander, next in line, is of Triassic red sandstone from the Midlands. However, this is visible only when the paint coating has flaked away (and the current paint coating looks like it has recently been repainted).

On the opposite (south) side of Queen Street, the shop frontages such as McDonald’s exhibit twentieth century substitutes for those earlier artificial stones, although some have upper facades of Portland Stone. The frontages display a bland paste peppered with chips of mineral calcite or marble, or quartz, floating in the matrix without the sorting and settling we would see in a normal sedimentary rock. This is terrazzo which is equally ‘plastic’ and mouldable.

Image source Welshleprechaun 16 April 2009 from Wikipedia

Staying on the south side of Queen Street. Although its frontage at street level is artificial, the Santander branch (yes there are two Santander branches very close to each other – one was formally a Bradford & Bingley branch; whilst the other was a branch of Abbey) high up on the front is of Portland Stone, freely carved with elephant heads. However, it is the style of the building which deserves note here. This simple carving fits the Art deco style of buildings we see in most towns and cities dating from the nineteen thirties.

At the end of Queen Street the statue of Aneurin Bevan (by Robert Thomas of Barry – 1987), stands on a plinth of dark red granite which is Balmoral Red from Finland. Years ago, this might have been Scottish Peterhead Granite from Aberdeenshire, but nowadays most granites come from overseas.

Question 4. Notice that there are two contrasting stones in the granite plinth of the statue of Aneurin Bevan, the difference being in the size of the feldspar crystals. Why do you think that there is a variation in the crystal size? Include the reason for your answer.

Cardiff Castle, Figure 16, as we see today was restored by the Butes between 1869 and 1921, but their walls are built upon the remains of the walls of a Roman fort. The old Roman walls are built of Jurassic Blue Lias Limestone probably from Aberthaw in the Vale of Glamorgan. A Victorian course of red missing word(s) - 1 caps the Roman walls and distinguishes them from the reconstructed walls which are built of two types of Carboniferous Limestones. The walls east of the main gate are pink limestone from Culverhouse Cross, but on the east wall this gives way to darker limestone from the Pentyrch-Creigiau area.

Question 5. What is the missing word(s) - 1? That is, examine the colour and (if you approach the wall) the texture, grain size, etc, to identify the stone used to cap the Roman walls. Getting this answer right may be difficult as there is only one course of this material. However, the colour is a bit of a giveaway.

The sloping floral display, at Location 10, is supported by part of Cardiff’s old town wall built mainly of missing word(s) - 2 probably robbed from the walls of the Roman fort or from Greyfriars Monastery nearby.

Question 6. What is the missing word(s) - 2? That is, examine the colour, texture, grain size, etc, to identify the stone used to construct/face this part of Cardiff’s old town wall. Ignore the red coloured bricks.

On your way to Location 11, which is near the statue of Judge Gwilym Williams of Miskin in front of the Law Courts, you should use the underpass in order to answer Question 14.

The ramp on the eastern exit of the underpass is faced with slabs of missing word(s) – 3 and emerges in front of the Law Courts, built in 1904 of missing word(s) – 4.

Question 7. What is the missing word(s) – 3? That is, examine the colour, texture, grain size, etc, to identify the stone used to face the wall visible as you emerge from under the road and is on your right as you start going up the ramp. This stone is a sandstone that you have already come across in its polished form.

Question 8. What is the missing word(s) – 4? That is, examine the colour, texture, grain size, etc, to identify the stone used in the construction of the Law Courts.

In front of the Law Courts stands the statue of Judge Gwilym Williams of Miskin (by William Goscombe John -1910), Figure 17, has an unpolished plinth of distinctive granite with large pink feldspar crystals from Shap in Cumbria.

On the traffic island between the Law Courts and the City Hall, is the South Africa War Memorial (by Albert Toft - 1909), which stands on a plinth of missing word(s) – 5 on a base of missing word(s) – 6 from Peterhead.

Question 9. What is the missing word(s) – 5? That is, examine the colour, texture, grain size, etc, to identify the stone used to make the plinth of the South Africa War Memorial.

Question 10. What is the missing word(s) – 6? That is, examine the colour, texture, grain size, etc, to identify the stone used in the base of the South Africa War Memorial.

We have collected the questions and logging requirement together so that they can be copied and pasted onto a single sheet should you want a paper version. However, you will need access to the full text of the cache description in order to answer them.

Question 1. Examine the columns at the entrance to the National Museum of Wales and determine the direction of the prevailing weather.

Question 2. Whilst examining the columns determine which column has the feature identified in Figure 2 and comment on what it probably is. (Note, count as number one the circular column on the far left as you face the entrance to the National Museum of Wales.)

Question 3. Whilst completing this EarthCache determine the location where Figure 3 was taken (it is the plinth of one of the statues referred to) and (by examining the colour, texture, grain size, etc) the type of stone.

Question 4. Notice that there are two contrasting stones in the granite plinth of the statue of Aneurin Bevan, the difference being in the size of the feldspar crystals. Why do you think that there is a variation in the crystal size? Include the reason for your answer.

Question 5. What is the missing word(s) - 1? That is, examine the colour and (if you approach the wall) the texture, grain size, etc, to identify the stone used to cap the Roman walls. Getting this answer right may be difficult as there is only one course of this material. However, the colour is a bit of a giveaway.

Question 6. What is the missing word(s) - 2? That is, examine the colour, texture, grain size, etc, to identify the stone used to construct/face this part of Cardiff’s old town wall. Ignore the red coloured bricks.

Question 7. What is the missing word(s) – 3? That is, examine the colour, texture, grain size, etc, to identify the stone used to face the wall visible as you emerge from under the road and is on your right as you start going up the ramp. This stone is a sandstone that you have already come across in its polished form.

Question 8. What is the missing word(s) – 4? That is, examine the colour, texture, grain size, etc, to identify the stone used in the construction of the Law Courts.

Question 9. What is the missing word(s) – 5? That is, examine the colour, texture, grain size, etc, to identify the stone used to make the plinth of the South Africa War Memorial.

Question 10. What is the missing word(s) – 6? That is, examine the colour, texture, grain size, etc, to identify the stone used in the base of the South Africa War Memorial.

Logging Requirement. There is one logging requirement to confirm that you visited the area. This requirement should be completed at Location 9. There is a statue in the street opposite Lloyds TSB. The statue is called ‘Mother and Son’ (by Robert Thomas – 2005). Either: -

a. State what toy is in the Mother’s string bag?

or

b. Take a picture of your GPS next to this statue (without giving away the answer to the above question).

Email the answers to the Questions 1 to 10 to us via the link in our profile. Please do not put the answers to the questions in your log entry, even encrypted. You do not need to wait for a reply before making your log. However, we request that you email the answers to us on the same day that you make your log. Any logs that do not fulfil all requirements will be deleted.

Logging Requirement. In addition to answering questions 1 to 10 there is one logging requirement to confirm that you visited the area. This requirement should be completed at Location 9. There is a statue in the street opposite Lloyds TSB. The statue is called ‘Mother and Son’ (by Robert Thomas – 2005). Either: -

a. State what toy is in the Mother’s string bag?

or

b. Take a picture of your GPS next to this statue (without giving away the answer to the above question).

Photographs from your visit are very welcome with your log. Feel free to upload any, except those that assist in answering the Questions, photographs you take during your visit to the EarthCache site in Cardiff City centre. We may even replace the current Figures using your pictures.

Congratulations to ‘sniffadogz’ for the FTF. We got the 'published' email at 13:36, on November 24, 2010, followed by the FTF 'find' log email at 16:30.

Please let us know (either in your log or through our profile) what you think of this urban EarthCache – was it useful in extending your knowledge of geology, was it too difficult, or any other constructive comments.

Picture credits are given under the appropriate Figure. If there is no credit we took the picture.

We would like to thank the South Wales Geologists Association for their assistance in setting up this EarthCache.

The Cardiff Public Art Register, 1st Edition 2008, was used to identify and provide details for some of the sculptures listed in this EarthCache.