Geology : Paleontology
PUTTING EVENTS IN ORDER
Scientists who study the
past try to put events in their proper order. When we discuss events that
happened in historical times, we often use dates or numbers, but we do not have
to do so.
Consider six historical events: the Wright brothers'
flight, the bicentennial of American independence, the First and Second World
Wars, the first astronaut landing on the moon, and when television became common
in homes. First, let's try to put these events in order. Our knowledge of the
words first and second tells us that the First World
War came before the Second World War. We may know or may have been told that the
landing of Neil Armstrong on the moon was seen by many people on television, but
there was no television around when the Wright brothers flew at Kitty Hawk.
Thus, we can order these three events: first Wright brothers' flight, then
television common in homes, then the landing on the moon. By a process of
gathering evidence and making comparisons, we can eventually put all six events
in the complete proper order: Wright brothers' flight, First World War, Second
World War, television common in homes, landing on the moon, and American
Because we have written records of the time each of
these events happened, we can also put them in order by using numbers. The
Wright brothers' flight occurred in 1903, the First World War lasted from 1914
to 1918, and the Second World War lasted from 1939 to 1945. Televisions became
part of our homes in the 1950's, Neil Armstrong walked on the moon in 1969, and
America celebrated 200 years of independence in 1976.
Written records are available for only a tiny fraction of the history of
Earth. Understanding the rest of the history requires detective work: gathering
the evidence and making comparisons.
Fossils, Rocks, and Time
By Lucy E. Edwards and John Pojeta, Jr.
Contents & Introduction
Events in Order
The Relative Time
The Numeric Time
The box above
shows six events that occurred during the twentieth century. The bottom
shows these events in relative order and numeric order.
In layered rocks
like these at Saint Stephens, Alabama, geologists can easily determine the
order in which the rocks were formed.