Catastrophic Events - Geologic Time

Catastrophic Events

Changes in Earth's History due to Catastrophic Events

• The changes in life forms, additions and extinction, are often accompanied by changes in environmental conditions on Earth.

• These environmental changes have been influenced by the impact of an asteroid or comet, climatic changes, and volcanic activity.

Impact of an asteroid or comet:

• Earth’s atmosphere protects the planet from many of the meteors that enter it, resulting in their burning up before striking the surface.

• At the end of the Mesozoic Era, when reptiles, early birds and mammals thrived, many groups of animals disappeared suddenly. Scientists hypothesize that possibly a large asteroid or comet impacted with Earth.

• This impact caused dust and smoke to rise into the atmosphere and cause climatic changes, as well as the dying of many forms of plant life and animals that depended on those plants for food.

• A major life form that disappeared at this time was the dinosaur.

Multiple Choice

__________________ protects the planet from many of the meteors that enter it, resulting in their burning up before striking the surface.

• Earth's Atmosphere

• Clouds

• Wind Resistance

• Gravity

Multiple Choice

At the end of which Era did dinosaurs go extinct?

• Paleozoic

• Mesozoic

• Cenozoic

Climatic changes

• Earth’s environments have many different climates even today. 

• Climate is an ever changing condition on Earth.

• Earliest life forms were influenced by the climates produced by the forming atmosphere and oceans of Earth.

Climatic changes - Paleozoic Era

• Life on land developed and flourished in the tropical climates and warm shallow seas during the Paleozoic Era.

• Throughout this era as different land environments formed and sea levels changed, new life forms developed. 

• Other life forms that could not adapt or find suitable conditions, especially many marine species, disappeared.

Climatic changes - Mesozoic Era

• During the Mesozoic era, many climate changes occurred due to plate tectonics and the movement of landmasses. 

• Plants and animals that survived through this time had structures and systems that allowed for greater adaptations, such as seed coverings for plant seeds and protective body coverings or constant internal temperature or animals.

Multiple Choice

When did many marine invertebrates go extinct?

• Paleozoic

• Mesozoic

• Cenozoic

Multiple Choice

Why did many marine animals go extinct at the end of the Paleozoic Era?

• The oceans dried up.

• There was no food left for the animals to eat.

• Animals could not adapt or find suitable conditions.

• The conditions were perfect, and the animals could not handle it.

Multiple Choice

During the Mesozoic era, many ____________ occurred due to plate tectonics and the movement of landmasses.

• Extinctions

• Climate Changes

• Adaptations

• Changes

Volcanic activity

• From the earliest days while Earth was forming to present day, volcanic activity has been part of the nature of this changing planet.

Volcanic activity - Precambrian

• During the Precambrian time volcanic activity was one of the most natural events, but lava flows, ash clouds in the atmosphere, and heat made conditions for life forms extremely difficult. Those simple life forms often did not survive these conditions. As continents collided and mountains built up due to plate tectonics, volcanoes also formed.

Volcanic activity

• Volcanic activity continued to be common in the Paleozoic era. those processes.

• During the rapid movement of plates in the Mesozoic era, collisions and subduction produced extensive volcanic activity around plate boundaries.

Volcanic activity

• Plate boundaries are still the location of much of Earth’s volcanic activity.

• Very explosive volcanic activity can send ash and dust high into the atmosphere where it is carried great distances around the Earth.

• The Sun can be blocked for long periods of time. This violent type of activity can disrupt many of Earth’s processes and ultimately the life forms that depend on.

How do volcanos interrupt Earth's processes?