Geology Reference
In-Depth Information
curs in some regions of the world when strong earthquakes occur. The ability to predict
an earthquake event could lead to lifesaving preparations such as evacuation.
Researchers have had little luck successfully predicting most destructive earthquakes.
Occasionally a large earthquake will be preceded by smaller earthquakes, slight
tremors, volcanic activity, or changes in land level relative to sea level. Such was the
case in Haicheng, China in 1975, when warnings a day before a large earthquake oc-
curred saved many lives. However, very few earthquakes send advance warning signals.
Current research around the Pacific Ocean focuses on trying to measure the amount of
strain being put on two crustal plates as they press against one another. (When the pres-
sure builds to a certain point and is released, an earthquake occurs; see Chapter 10 for
details.) Unfortunately, many complex factors lead to an earthquake event, which makes
the effort to predict them very challenging. Fortunately, scientists love a good challenge!
Climate change
In looking into earth's past, one area of intense study is
paleoclimatology,
the study of
past climates. Scientists called
paleoclimatologists
take long, cylinder-shaped samples
called
cores
from ice sheets. In these ice cores, they find trapped gases and dust from
the ancient atmosphere that provide clues to the earth's temperatures long ago. Cores
of sediments in the bottom of lakes or the ocean may have fossil remains of microscopic
organisms. These remains of plant and animal life help scientists called
paleoecologists
build a picture of the ancient environment and past climates.
These are just two of the types of records scientists use to understand earth's past cli-
mate conditions. By combining multiple records and including different types of data,
paleoclimatologists and paleoecologists build a picture of climate change throughout
earth's history.
Through these studies, scientists have learned that the earth's climate has gone through
dramatic shifts of warming and cooling in the past. Factors including earth's orbital
characteristics and the position of the continents are thought to have affected the cli-
mate.
By building a more complete understanding of what changes occurred in the past, sci-
entists hope to be able to predict what changes may occur in the future, particularly in
light of industrial civilization's measurable impacts.
Out of this world: Planetary geology and the
search for life
