Limestone high quality quarried limestone, called Indiana limestone. Many famous buildings in London are built from Portland limestone. Limestone was also a very popular building block in the Middle Ages in the areas where it occurred, since it is hard, durable, and commonly occurs in easily accessible surface exposures. Many medieval churches and castles in Europe are made of limestone. Beer stone was a popular kind of limestone for medieval buildings in southern England. Limestone and (to a lesser extent) marble are reactive to acid solutions, making acid rain a significant problem to the preservation of artifacts made from this stone.
Bishop's Frome Limestone basin between the Silurian and the Devonian periods. The rock was formerly known as the Psammosteus Limestone after a characteristic fossil fish recorded from it; "Psammosteus anglicus". The fossil remains were subsequently shown to have been wrongly identified and belong in fact to "Traquairaspis symondsi". Its modern name derives from the Herefordshire village of Bishop's Frome. Its thickness is variable ranging from 2m up to 8m. Bishop's Frome Limestone The Bishop's Frome Limestone (or Bishops Frome Limestone) is a rock unit within the Raglan Mudstone Formation of the Old Red Sandstone occurring in the border region between England and South