Download Mass Extinctions

Catastrophic Events
8.E.6A.3 Construct explanations from evidence for how catastrophic
events (including volcanic activities, earthquakes, climate changes, and
the impact of an asteroid/comet) may have affected the conditions on
Earth and the diversity of its life forms
Mass Extinctions
• Impacts, climate changes, and volcanism can create rapid and quick changes
to environmental conditions
• Many Organisms cannot adapt to these changes resulting in the extinction of
those species
Impact of an asteroid or comet
• Earth’s atmosphere protects the planet from many of the meteors that enter it resulting
in the burning up before striking the surface
• There is evidence of many impacts throughout Earth’s history
• Impacts have had both local and large-scale effects on the environment and biodiversity
• At the end of the Mesozoic Era, a large asteroid or comet hit Earth
• Caused dust and smoke to rise into the atmosphere
• The Dust and smoke caused climatic changes, death of plants, animals died because of lack of
vegetation
• There is a crater off Mexico’s Yucatan Peninsula which is dated about 65 mya
Climatic changes
• Earth’s environments have many different climates
• Climate is an ever-changing condition
• Earth’s life forms were influenced by the climates produced by the forming atmosphere
and oceans
• Life on land developed and thrived in the tropical climates and warm shallow seas during
the Paleozoic Era
• In the Paleozoic, there were different land environments and sea levels changed and new life forms
developed
• Some life forms could not adapt or find suitable conditions, especially many marine species
Cont.
• During the Mesozoic Era, many climatic changes occurred due to plate tectonics and
movement of landmasses
• Plants and animals that survived through this time had structures and systems that
allowed for greater adaptations
• Seed coverings for plant seeds
• Protective body coverings
• Constant internal temperature for animals
Cont.
• In the Cenozoic Era, Climate conditions continue to change
• Major ice ages cause the climate to become much cooler as ice sheets and glaciers
covered many areas of Earth
• Many Mountain ranges formed causing climate differences due to elevation and due to
location near those ranges
Volcanic Activity
• Volcanic activity has been part of the nature of the changing planet
• As continents collided and mountains built up, volcanoes formed
• During the Precambrian time volcanic activity was one of the most natural events
• Lava flows, ash clouds in the atmosphere, and heat made conditions for life extremely difficult
• Volcanic activity continued to be common in the Paleozoic
Cont.
• Rapid movement of tectonic plates in the Mesozoic Era and the collisions and
subduction produced extensive Volcanic activity around plate boundaries
• Plate boundaries are still the location of much of Earth’s volcanic activity
• Very explosive volcanic activity can send ash and dust into the atmosphere where
it is carried great distances around the Earth
• The Sun can be blocked for long periods of time
• Violent type of activity can disrupt many of Earth’s processes and ultimately the life forms
that depend on those processes