The fountain stands on the corner of St George's Colegate churchyard at the intersection of Colegate with Muspole Street. The square bowl rests on a column -restored at its base - with a square metal spout and under a domed canopy supported by worn brackets and crowned with a cross.
(More information on the fountain further down. BUT first the earth lesson.)
Portland Stone formed at the end of the Jurassic period, around 145 million years ago when what is now Portland, was much closer to the equator than it is today.
A chemical reaction in the warm, shallow seas where Portland Stone was forming caused calcium and bicarbonate ions to combine, forming a 'muddy' calcareous precipitate. Minute particles of sand or organic detritus, such as shell fragments, lying on or in suspension close to the sea floor, acted as nuclei which gradually became coated with this fine-grained calcium carbonate.
Over time more calcium carbonate accumulated around these nuclei in concentric layers, forming small calcareous spheres (less than 1mm diameter). Countless billions of these spherical sediments, called 'ooids' or 'ooliths', ultimately became buried and partially cemented together by more calcium carbonate, resulting in the oolitic limestone we now call Portland Stone.
Fortunately, the degree of cementation in Portland Stone is sufficient to allow it to resist the detrimental effects of the weather, but it is not so well cemented that it can't be readily worked (cut and carved) by masons. This is one of the reasons why Portland Stone is so favoured as a monumental and architectural stone.
Towards the end of the Jurassic Period, around 145Ma (million years ago), because of continental drift, the land that makes up much of what is Southern England was located far south of its present global position, at about 38o north of the Equator. What is now Portland was positioned at a palaeolatitude similar to that of modern Florida or Israel, where the “Mediterranean” type climate was likely characterized by warm wet winters and hot dry summers.
Portland Stone formed in a specific type of marine environment,known as a carbonate ramp,on the floor of a shallow, warm, sub-tropical sea,not too far from land, as evidenced by carbonaceous driftwood trace fossils, which arenot uncommon. As seawater was warmed by the Sun, its capacity to hold dissolved gas was reduced;as a consequence, dissolved carbon dioxide CO2was released into the atmosphere (as a gas) disrupting the chemical mass balance in the water. In response, discrete calcium cations(Ca2+)and bicarbonate anions(HCO3-)within the supersaturated seawaterbonded together,forming calcium carbonate(CaCO3)as a solid precipitate, according to the formula:
Using the Folk classification scheme, geologists categorize Portland Stone as mainly porous oosparite.
Portland Stone is one of the youngest Jurassic rocks, laid down just before the end of the period. Contemporary(aragonitic) oolitic limestone, that might be considered a modern analogue for Portland Stone is forming today in warm, lime-rich waters, such as those found in the coastal margin of the Persian Gulf and in the Atlantic, on the Bahamas’ Banks.
If you like you can dive deep into the material by checking this link.
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Questions
1. Answer the questions under by visiting the Coordinates.
A. What type of stone is a Portland stone?
B. How many million years ago was it formed in the shallow seas? (Answer can be found in text.)
C. Can you say anything on the condition of the fountain, and why? Give several reasons why. (Answer can be found at GZ)
D. Do we have any fossils in the stone used for the fountain. (Answer can be found at GZ)
E. What type of stone is used for the basin and the slab above it with the engravings on it? (Answer can be found at GZ)
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Drinking Fountain - St George's
Its design fits with the drinking fountains introduced from the 1860s as the Victorians became concerned about the supply of drinking water as a result of their concerns about the supply of cheap liquor for the poor, reinforced by their awareness of polluted water as a cause of cholera in the 1850s, see NFnrNOR042. It was described in the Builder for 1860, December 1st 1860 (with the engraving). This fountain is executed in Portland Stone, except the basin, supported on an octagon pedestal, and lying in a cluster of waterlilies. The octagonal canopy over the basin, with battlements and finial, has waterlilies carved on its pendants, and the water issues from the centre of a lily. On each side of the octagon pedestal are arched troughs for dogs. Above the basin and under the canopy, the following lines are engraved in old English characters on a slab... Below are initials of the donor and the date: JCB 1860″.
Inscriptions: Wayfaring man for thee this faucet was given/A channel to impart the boon of heaven/ Drink and thank God! and in this water trace /An earnest of His love and emblem of His Grace
