<P> It is sometimes said that its name is derived from legends pertaining to King Arthur, such as the reference in Y Gododdin . Some support for this may be provided by several other hilltop and mountaintop features in Britain which bear the same or similar names, such as the peak of Ben Arthur (The Cobbler) in the western highlands, sometimes known as Arthur's Seat, and Arthur's Chair on the ridge called Stone Arthur in the Cumbrian lake district . There is no traditional Scottish Gaelic name for Arthur's Seat in Edinburgh, but William Maitland proposed that the name was a corruption of Àrd - na - Said, implying the "Height of Arrows", which over the years became Arthur's Seat (perhaps via "Archer's Seat"). Alternatively, John Milne's proposed etymology of Àrd - thir Suidhe meaning "place on high ground" uncomfortably requires the transposition of the name elements . </P> <P> Arthur's Seat is the largest of the three parts of the Arthur's Seat Volcano site of special scientific interest (the other parts being Calton Hill and the Castle Rock) which is designated to protect its important geology (see below), grassland habitats and uncommon plant and animal species . </P> <P> Like the rock on which Edinburgh Castle is built, it was formed by an extinct volcano system of Carboniferous age (lava samples have been dated at 341 to 335 million years old), which was eroded by a glacier moving from west to east during the Quaternary (approximately the last two million years), exposing rocky crags to the west and leaving a tail of material swept to the east . This is how the Salisbury Crags formed and became basalt cliffs between Arthur's Seat and the city centre . From some angles, Arthur's Seat resembles a lion couchant . Two of the several extinct vents make up the' Lion's Head' and the' Lion's Haunch' . </P> <P> Arthur's Seat and the Salisbury Crags adjoining it helped form the ideas of modern geology as it is currently understood . It was in these areas that James Hutton observed that the deposition of the sedimentary and formation of the igneous rocks must have occurred at different ages and in different ways than the thinking of that time said they did . It is possible to see a particular area known as Hutton's Section in the Salisbury Crags where the magma forced its way through the sedimentary rocks above it to form the dolerite sills that can be seen in the Section . </P>

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