Precipitation peaked when the orbit was at its most eccentric, producing deep lakes that left layers of black shale in eastern North America. (ldeo.columbia.edu)
In Western Australia, they found preliminary evidence of these oxygen whiffs in black shales deposited on the seafloor of an ancient ocean. (sciencedaily.com)
Interspersed in the red stone were narrow bands of black shale containing petrified fish, from a time when a deep lake covered the area. (discovermagazine.com)