Age 6 - Small Flood Basalt
Geological / environmental event
Lava plains open up between the tropical and arid lands near the West coast.
The small flood basalt event has mild global effects. First a short period of dimmed solar intensity due to more particles in the atmosphere, and cold. All plants on Iris have a tolerance for extended periods of darkness due to a long night and day cycle, so most plants manage to get by on reduced solar energy. The ones that struggle the most are greener plants, especially aquatic ones near the equator as they need intense solar energy. Organisms within a narrow range of temperature tolerance that cannot migrate or send their gametes to new lands quickly are at the greatest risk of extinction at this point. This cold snap is likely to affect land organisms more and species near the surface of the water that are reliant on solar energy for food and warmth, and to some extent deeper ocean species that rely on a rain-down of organic detritus.
This is followed by a swing in the other direction, as atmospheric particles settle on the surface increased solar energy is allowed back in to be trapped by greenhouse gases that have been released by the volcanic event causing a period of abnormally hot weather. CO2 that has been dissolving into the oceans raise it's pH slightly, not to catastrophic levels but enough to put stress on a few species, for example those with shells as shells dissolve at a faster rate and become more costly to grow and maintain (less affected are those with concealed shell/non-living skeletal parts) and especially at lower depths due to a reduced compensation depth for these mineral compounds. Algal blooms cause toxic and anoxic lesser events, caused by a reduced population of herbivores affected by the initial cold snap.
Conditions return to those pre-event within the first few thousand years of Age 6.
Extinctions:
