Geology Reference
In-Depth Information
This darkened atmosphere may also be very cold and difficult to breathe in — like a
day of heavy smog in modern cities, but a day that lasts for many years.
3. Plant life is affected first.
The combination of acid rain, cooler temperatures, and
absence of sunlight shuts down the process of photosynthesis and brings plant life to
a halt.
4. Herbivores are affected next.
Without the plants to support them, herbivorous an-
imal species begin to suffer.
5. The entire ecosystem collapses.
As the plants and herbivores disappear, animals
that depend on them (carnivores) also suffer. Eventually entire food webs have been
affected and begin to collapse.
Keep in mind that mass extinction does not occur in one day. The sequence of events
following an impact may continue for many hundreds or thousands of years following
the impact event itself. The species that can't adapt to a new way of life will die out.
Lava, lava everywhere: Volcanic eruptions and
flood basalts
Basalt rocks formed by the cooling of lava indicate that at times in earth's past, volcanic
activity occurred on a massive scale. Entire regions of the continents, called
provinces,
are covered by layers of basalt rock many miles deep. Regions of the modern continents
that are covered in these flood basalts are illustrated in Figure 22-1.
Figure 22-1:
Re-
gions of the mod-
ern continents
covered in flood
basalt rock layers.
