Although modern geology appeared in the eighteenth century, the Earth was already studied by the Greco-Roman philosophers. The Greek philosopher Theophrastus (371 to 287 BC) described and classified minerals according to their physical properties. The Roman writer Pliny the Elder (23-79 AD) described minerals, crystals and fossils. Also some medieval Muslim scholars proceeded in the field of geology. Al-Biruni (973 – 1048) described the geology of the Indian subcontinent and believed this area was once a sea. Avicenna (981 – 1037) described the formation of mountains as an interplay between tectonic forces and erosion . He believed that mountains had made this form which aproved that the Earth is very old. The Chinese scholar Shen Kuo (1031-1095) independently came to similar ideas.
In Europe one of the first naturalists was Leonardo da Vinci (1452-1519). Da Vinci understood that the fossil shells that he found in the Apennines are indeed remnants of life from earlier times. The Venetian physician Georgius Agricola (1494-1555) was particularly interested in the mining industry. He shared the first rocks in a methodical way: in four groups of consecutive age and consolidation. Nicolaus Steno (1638 – 1686) investigated how rock layers are formed and proposed three laws, with which he was the founder of the stratigraphy.