This quartz-pebble conglomerate is from one of the oldest layers of the Huronian Super-group. It formed as a gravel bar in a river, perhaps during a flood. The rock contains the heavy minerals pyrite (called “fool’s gold”) and uraninite (a uranium mineral), which were originally particles carried by the river. These minerals could not have survived in the presence of oxygen. They are part of the evidence for an oxygen-poor atmosphere 2.5 billion years ago.
Topic: Earth Science
Keywords: Atmosphere, Geology, Stratigraphic--Huronian, Oxygen, Paleoclimatology, Pyrites, Uraninite