Permian-Triassic Boundary (IMAGE) Université de Genève Caption Permian-Triassic boundary in shallow marine sediments, characterised by a significant sedimentation gap between the black shales of Permian and dolomites of Triassic age. This gap documents a globally recognized regression phase, probably linked to a period of a cold climate and glaciation. Credit © H. Bucher, Zürich Usage Restrictions None License Licensed content 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.