Limestone is a sedimentary rock that contains a high percentage of calcium carbonate. It is formed by the accumulation of shell, coral, algae and fecal debris overtime through the rock formation process. There are many types of limestones available, whether they are French or German imports or quarried here in the UK. However, the most commonly used in South Wales and the West of England are:– BathstoneBath Stone is an Oolitic Limestone comprising granular fragments of calcium carbonate. Originally obtained from the Combe Down and Bathampton Down Mines in Somerset, its warm-honey colouring gives the World Heritage City of Bath its distinctive appearance. An important feature of Bathstone is that it is a ‘freestone’, so-called because it can be sawn or ‘squared up’ in any direction, unlike other rocks such as slate, which forms distinct layers and is unsuitable to carve.– Blue LiasThe Blue Lias is a geologic formation in southern, eastern and western England and parts of South Wales. The Blue Lias consists of a sequence of limestone and shale layers, laid down between 195 and 200 million years ago. Blue Lias is useful as a building stone, and as a source of lime for making lime mortar. Since the mid-nineteenth century, it has been used as a raw material for cement, in South Wales, Somerset, Warwickshire and Leicestershire. Occurrences of Blue Lias can be found in buildings local to its source as well as the local churches and cemeteries (where it is traditionally used in tombstones). It is popular in modern-day surroundings where it is still used in the construction of new housing developments and extensions for existing buildings in conservation areas. Blue Lias is mainly used in flooring, walling and paving slabs – both coursed and layered. It is evident too in the making of flagstones and cobbles.– PortlandPortland stone is a limestone from the Tithonian stage of the Jurassic period quarried on the Isle of Portland, Dorset. The degree of cementation in Portland Stone is such that the stone is sufficiently well cemented to allow it to resist weathering but not so well cemented that it can’t be readily cut and carved by masons. Portland Stone is favoured as a monumental and architectural stone. It has been used extensively as a building stone throughout the British Isles, notably in major public buildings in London such as St Paul’s Cathedral and Buckingham Palace. Limestones are not consistent in colour – Portland is almost white in colour, Bathstone is more creamy gold in appearance and Blue Lias is grey blue. It is assumed that all stone is quarried, however, the interesting fact about Bathstone is that at present it is mined rather than quarried like Portland and Blue Lias. Limestone has been extensively utilised as a building material. The city of London is mainly built from Portland stone, as well as Cardiff Civic Centre. When you arrive in the City of Bath, the majority of buildings are made of Bathstone including some of the city’s most famous landmarks – the Royal Crescent and The Circus. Due to its characteristic, Blue Lias is mainly used for walling throughout South Wales and South West England.