Doubt regarding Oil shale geology Hi there i just wanted a clarification regarding One theory supposes that the organic material in the Irati oil shale originates from algae deposited in a freshwater to brackish lacustrine environment In the above sentence what does the phrase freshwater to brackish lacustrine environment mean Does it mean oil shale originates from algae deposited in a freshwater environment or does it mean oil shale originates from algae deposited in a brackish lacustrine environment or does it mean something else