was dug in the Clee Hills and at Wombridge in the 16th century. Wenlock had a famous copper-mine in the reign of Richard II, and in the 16th century was noted for its limestone. As the forest areas were gradually cleared and brought under cultivation, the county became more exclusively agricultural. In 1343 Shropshire wool was rated at a higher value than that of almost any other English county, and in the 13th and 14th centuries Buildwas monastery exported wool to the Italian markets. Shropshire had never been distinguished for any characteristic manufactures, but a prosperous clothing trade arose about Shrewsbury and Bridgnorth, and Oswestry was famous in the 16th century for its "Welsh cottons", cheap woolen cloth in which the nap was raised, or "cottoned" by carding. The Industrial Revolution Shropshire is the "geological capital" of the UK, as just about every rock type in Northern Europe is found within its borders, as are coal, lead, copper and iron ore deposits. In addition to this, the River Severn flows through the county and has been used for the transportation of goods and services for centuries. A result of this was that the Ironbridge Gorge became a focal point of new industrial energies in the 18th century. Coalbrookdale, a small area of the Gorge, has been claimed as the birthplace of the Industrial Revolution, because of Abraham Darby I's development of coke-smelting and ironfounding there in the early 18th century. The towns of Broseley and Madeley were centres of innovation during the late 18th century. In Broseley, John Wilkinson pioneered precision engineering by providing cylinders for Boulton and Watt's improved steam engines, and by boring cannons with greater accuracy and range. He also constructed the first iron boat, launched in 1787. It was in nearby locations where key events of the Industrial Revolution took place. Coalbrookdale is where modern iron smelting techniques were developed, Ironbridge is where the world's first iron bridge was constructed in 1779, to link Broseley with Madeley and the Black Country, and Ditherington in Shrewsbury is where the world's first iron framed building was built, the Ditherington Flaxmill. Other places notable for early industry are Jackfield for tiles and Coalport for china. Later, Broseley and Madeley became notable for their continuation of trade in the field of bricks and tiles, which became a staple to the booming building trade, and millions of Broseley clay pipes were