December GSA Today Cover Image (image) Geological Society of America Share Print E-Mail Caption Hydraulic gold mining by Romans nearly 2,000 years ago left this dramatic example of human modification of the landscape at Las Médulas, Spain, a UNESCO World Heritage Site. Water obtained from surrounding mountainous watersheds was used to undermine the >100-m-thick Miocene alluvial fan sediments here until they collapsed -- a process called ruina montium, loosely translated as ruin the mountain -- and then washed to separate the gold. Tailings total ~90 Mm3. Photo by Justino Diez. Credit Photo by Justino Diez. Usage Restrictions Credit to author and mention of the article in the December GSA Today. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.