20. Compare the geologic times during the emergence
of the Hawaiian Island chain to present time in terms of the position of
closest continents and types of life forms present in the rest of the world.
I. Positions of the continents at the time of Hawaiian Islands' emergence
are basically the same as today.
For over 200 million years the major continents of the earth have been moving
apart, from the ancient super-continent of Pangaea to their present-day
locations through the the process of plate tectonics. (See discussion in
Learning Objective 16 and Figure 20-A)
II. THE HAWAIIAN ISLANDS are the most remote island chain in the
world. They are about 2,500 miles from the closest continental area,
North and Central America, and the nearest island chain, the Marquesas,
to the south-east.
Asia, southeast Asia, and Australia/New Zealand are 4,000 miles away. Original
plant colonists, or immigrants, had to successfully disperse across at least
2,500 miles of open ocean! (See Figure 20-B)
III. THE TYPES OF LIFE FORMS that existed on the earth when the Hawaiian
Islands arose from the ocean.
A. The time frame for the earliest members of the Hawaiian
Island chain (now remnants islands from Nihoa to Kure) is about 35-45 million
years. (See Figure 16-D)
B. Of present-day larger Hawaiian islands, the oldest, Kaua'i, is
about 3-5 million years old and the Big Island 1 million or less. (See Figure
C. First mammals and flowering plants were present over 100 million
years ago. About 30 million years ago, flowering plants became the
dominant plant form on earth. Human-type life was present about 4 million
years ago, a little after the formation of Kaua'i. (See figure 20-A).
A. The Hawaiian Island Chain arose from the floor of
the Pacific Ocean after the world's great continents were essentially
in the position they are found today, and all the recent plant
and animal life forms were also present on the earth.
B. Like a gigantic scientific experiment, a new chain of islands,
the Hawaiian, arose out of the Pacific Ocean, after most of the world as
we know it today was formed. We are talking about very recent geologic
time for the origin of the Hawaian Islands!
C. What happened to these large sterile surfaces after they arose
from the ocean floor? We know that initially they had no lifeforms because
no life can withstand the 1000 degree heat of molten lava. When the first
Polynesians discovered them, the islands were teeming with life forms they and
no one else had ever seen. How did this happen?
For further information about geologic time, visit this museum site in Berkeley, California.
Click here to leave your comments and suggestions.
[Learning Objectives Numerical Index]