An EarthCache provides an earth science lesson through a visit to a geological feature. This EarthCache concerns the weathering of Limestone. There is no physical container to find, just information.

About your location

The Neptune Fountain in Cheltenham is worth a visit all year round - it is one of the iconic monuments in this Regency Town.

Purported to have been modelled as an ode to the Trevi Fountain in Rome, Italy (although that has never been historically verified) The Neptune Fountain sits outside the Municipal Buildings on The Promenade.

Unveiled in 1893, it was designed by engineer Joseph Hall and carved from Portland Stone by sculptor Richard Lockwood Boulton and his sons. It is fed from the River Chelt, which flows beneath the Fountain in a culvert which diverts the River through the Town to emerge in Sandford Park. At night, it is beautifully lit, creating an eye-catching focal point on The Promenade.

The Fountain is cleaned, maintained and cared for by Cheltenham Borough Council, and underwent a full restoration in 1989.

(info from visit Cheltenham)

Please read the information below as it will help you to answer the EarthCache questions.

What is Limestone?

Limestone is a sedimentary rock. This sediment is formed by very many tiny particles which laid down deposits over millions of years. These were composed mainly of skeletal fragments of marine organisms such as coral and molluscs. As the sediment layers build up they are pressed together to form sedimentary rock.

Limestone has numerous uses: as a building material, an essential component of concrete (Portland cement), as aggregate for the base of roads, as white pigment or filler in products such as toothpaste or paints, as a chemical feedstock for the production of lime, as a soil conditioner, or as a popular decorative addition to rock gardens.

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Weathering

This describes the breakdown of rock through exposure to the atmosphere. It can happen in three main ways...

1. Chemical Weathering

Rainwater is naturally slightly acidic because carbon dioxide from the air dissolves in it. Minerals in rocks may react with the rainwater, causing the rock to be weathered.

Some types of rock are easily weathered by chemicals. For example, limestone is made up of a mineral called calcium carbonate. When acidic rainwater falls on limestone, a chemical reaction happens. New soluble substances are formed in the reaction. These are washed away and the rock is weathered.

Chemical weathering can hollow out caves form and make cliffs fall away.

2. Biological Weathering

This can cause the breaking and/or crumbling of the stones by tree roots, plants or animals. Also common is the damage caused by lichens or organisms growing on the surface of rocks. Lichen takes the nutrients it needs from the surface of the limestone. Changes in the composition of the rocks can weaken them.

3. Physical Weathering

Weathering from physical factors can change the shape of the rock, rather than the actual composition. Heat can expand stones, while cold will cause contraction. This process over a period of time will cause the stones to fracture and crack. Rainwater can then also seep into cracks in the rock, and, if frozen, will expand and make these cracks bigger and wider.

Wind can also affect loose grains of stone, causing more damage