Since Earth is made up of rock, no one "discovered" a first rock. In fact, it is challenging to know who the first person to think critically about rocks might have been. Like all science, the study of Earth has evolved with technology and human understanding. Generally, the first advanced thoughts around Earth (including mineralogy, cartography, geography, and geology) are attributed to ancient Greece. The oldest known maps are preserved on 2300 B.C. Babylonian clay tablets. Xanthus of Lydia (modern day Turkey) and Herodotus of ancient Greece were historians who occasionally wrote about geology and the natural world during the 5th century B.C. (500-400 B.C.). The concept of a spherical Earth was widely accepted in Greece around 350 B.C.. Strabos of Greece wrote a book titled, "Geography" before 24 A.D. Pliny the Elder of Rome wrote one of the earliest encyclopedic works on natural and geographic phenomena shortly before his death in 79 A.D. Modern geology is attributed to James Hutton from Edinburgh, who dedicated himself to the study of rocks beginning in 1768. He laid the foundation for scientific geology.