Geoscience Reports
Winter 1985/86 No. 6
EARTH IN MOTION: PLATE TECTONICS AND CONTINENTAL DRIFT
The Origin of the Theory
During the past 100 years there have been an amazing number of scientific discoveries accompanied by a great variety of new theories. One of the more novel and yet powerful of these is the concept of continental drift. In 1912 Alfred Wegener, a German meteorologist, proposed that the continents of our modern world were once fitted together in a "supercontinent" called Pangea. At some time in the Earth's past history, the super-continent broke up and the pieces drifted apart, eventually resulting in the present arrangement of the continents (1). Wegener's hypothesis was largely rejected by other scientists for 60 years until accumulating evidences begged a more serious treatment of the hypothesis. The fit of the present continents (including the continental shelves) similar to a jigsaw puzzle is quite remarkable. (See Figure 1.) This was strong evidence in support of Wegener's theory.
Evidence Supporting The Theory
One support for continental drift involves mineral and fossil
deposits now separated by oceans but which would have been closely associated in a
supercontinent such as Pangea. Some specific fossil examples include the freshwater
reptile Mesosaurus which is found only in Brazil and Africa and the fossil fern
Glossopteris found in Africa, India, Australia, Antarctica, and South America (1). A
classic example of mineral deposits is diamonds in the same type of parent rock in both
eastern Brazil and western Africa (1). In Pangea, these fossils and mineral deposits would
have been close together.
A second support for continental drift is sea floor spreading. The
present rate of spreading along the Mid-Atlantic Ridge is estimated to be in the range of
1.5 - 5 cm per year (1). This means that the Americas and Europe/Africa are slowly
becoming more widely separated. It is interesting to note that this rate has often been
assumed to be fairly constant. This would lead to time calculations of millions rather
than thousands of years since sea floor spreading began. Flood geologists generally
believe that this land mass movement may have occurred much more rapidly as a result of
the Noachian Flood. Violent upheavals could produce a spreading of the sea floor that was
initially rapid and subsequently diminished to the present slow rate.
Magnetic direction changes evident in the rock along the Mid-Atlantic
Ridge constitute a third line of support for continental drift. As solid rock is formed
from cooling magma (molten rock), the crystals in the rock align themselves with the
existing lines of Earth's magnetic field. This process in effect gives us a
"fingerprint" of the earth's magnetism at the time of cooling. The paleomagnetic
alignments of the continents are not orderly in the modern world; yet, in the arrangement
of Pangea, the rocks of each continent show closely related paleomagnetic orientations
(1).
Objections to the Theory
Despite the evidence for continental drift listed above, there are also data which appear contradictory to some aspects of the theory. Therefore, the theory has a number of opponents. An objection voiced by some is the difficulty encountered in finding a mechanism whereby huge masses of land such as continents could be moved. One potential mechanism is discussed by the theory of plate tectonics. The basic thrust of this theory is that the Earth's crust is composed of relatively thin plates which "float" on the more dense "plastic" rock below (see Fig. 2). Thus, if continents are found on different plates which move independently, it is reasonable to postulate that the plate arrangement may have been different at some time in the past. Many scientists believe that a great number of the Earth's surface features resulted from past movement of large portions of the crustal plates.
Plate Tectonics Examined
Plate tectonics is much more than a prop for the theory of
continental drift, however. In fact, the plate tectonics viewpoint is extremely useful in
providing reasonable explanations for a number of Earth processes. Seismic activity found
along the San Andreas Fault in California is an excellent example. As the Pacific Plate
collides and rubs against the North American Plate, pressure builds and eventually
slippage occurs, causing an earthquake. This type of activity is usually more frequent
where two plates meet. Specific examples include the San Francisco Earthquake of 1906, the
Alaskan Earthquake of 1964, the earthquake in Huaras, Peru in 1970, and the China
Earthquake of 1976.
Volcanoes are another phenomenon that frequently occurs along the
borders of plates as hot magma from deep within the earth pushes its way upward near the
plate boundaries. The "Ring of Fire" which surrounds the Pacific Plate is a good
example of this type of volcanic activity. In this ring, volcanoes nearly circle the
Pacific Ocean. (See Fig. 3.)
Island arcs such as Japan and the Philippines are often said to be the
result of one plate pushing under another in a process called subduction (1). It is
interesting to note that deep ocean trenches are generally found close to these areas of
subduction. With the processes of subduction and sea floor spreading working at opposite
edges of a plate, one can easily envision shifting of entire plates as one edge is melted
away while the other is expanding.
A final result of the plate tectonics process which we will deal with
is mountain building. The collision of two plates often causes a mountain range uplift in
much the same way that ridges form when someone pushes a carpet from the edge. This type
of activity is associated with the formation of such notable mountain ranges as the Sierra
Nevada, the Andes, and the Himalayas. Creationists; often postulate that most of the
uplift of these mountains occurred as the result of the violent activity of the Noachian
Flood and post-flood adjustments.
Summary
The theories of continental drift and plate tectonics are useful in explaining a number of physical situations which we encounter on Earth today. Both theories may be satisfactorily incorporated in a creationist perspective. The processes of continental drift and mountain building could have been accelerated as a result of the Flood's violent effects upon the stability of the Earth's crustal plates.
References
Bibliography
About The Author
Eric Magi graduated from Pacific Union College with a M.A. in Biology Education in 1979. Currently Eric is teaching science and math at Collegedale Academy in Collegedale, Tennessee. The previous six years Eric taught science and math at Mt. Ellis Academy in Bozeman, Montana.
EDITORIAL
Need Assistance?
Dial: (YOU) TAK-TIME
As a teacher, I know that preparing for the daily tasks is a
full-time job that requires most of my energy. When approached by a new subject area, in
which I know very little, I am inclined to go the route of least resistance. Is this route
the best for me and my students? Sometimes yes, but, most of the time, no. If the choice
of least resistance is not the answer, then what is?
Over the course of time I have found that the best choice is to take
time to discover the resources (people, books, societies, et cetera) within my reach and
then utilize them to my students' advantage! By taking a little time, I have found gold
mines of information within the people around me. Their hobbies or work have often filled
my needs.
Societies are another source of information and assistance. For the
price of a postage stamp and a sheet of school letterhead, many state and federal
societies will send you information packets on almost any subject. This is especially true
for the geological societies. The state and federal geological societies will go to great
lengths in order to assist the school teacher.
Rock Shop
Another important and often overlooked area of help in earth
sciences is the local rock shop! By taking a little of your time to talk to these people,
you can generally get information about local areas for field trips. Many of these people
would accept an offer to come to the classroom and share their interests, if only asked.
Admittedly all of these efforts take time, but the time is well spent
Not only are your personal horizons expanded but also those of your students.
In closing I will leave you with an address that will unlock the world
for you and your students! On school letterhead (YOU MUST USE SCHOOL LETTERHEAD!) simply
write a letter requesting the TEACHER'S PACKET to the following address:
Geologic Inquiries Group
U.S. Geological Survey
Reston, VA 22092
(703) 860-6517
REM: Time is like oats: sown wisely, a bountiful harvest will be reaped.
NEWS NOTES:
BRISCO 1985 Considers Inspiration
About 25 Adventist scientists and theologians met from August 9 -
13, 1985, to discuss the nature of inspiration and revelation and how they relate to
current issues in the church. The Black Hills Health and Education Center, a
self-supporting medical and educational institution located about 20 miles south of Rapid
City, South Dakota, played host to the annual meeting of BRISCO. (BRISCO is an acronym for
the Biblical Research Institute Science Council). Participants enjoyed the rural setting,
a mixture of forested hills and planted fields.
Most of the papers presented dealt with one of three general topics.
One group of papers considered the nature of inspiration as revealed in the witness of
scriptural writers. Another group of papers dealt with the nature of inspiration as
illustrated in the life and writings of Ellen White. A third group of papers considered
specific portions of the book of Genesis. Two scientists presented papers, including Dr.
R. H. Brown of GRI, who discussed radiocarbon dating. Each presentation was followed by a
discussion, many of which were continued by small groups during breaks in the schedule.
Sabbath Included
One new feature of the meetings, which repeatedly received favorable
comments, was the inclusion of a Sabbath in the program. The opportunity of worshiping
together brought a sense of fellowship which probably would not have been possible
otherwise. Fellowship was enhanced by the fact that no formal papers were scheduled for
the Sabbath, making it possible for new friendships to be renewed, as well as for ideas to
be exchanged and discussed.
On Monday, the group went on a tour of the area, led by Dr. Harold
Coffin of GRI. The first stop was near the town of Hot Springs, at a Pleistocene mammoth
site where the skeletons of more than 30 mammoths have been found. The site is interpreted
to have been a spring-fed pond, where the elephants were trapped and died. Another
interesting stop was Jewel Cave National Monument, a very extensive system of caverns and
tunnels under the Black Hills a few miles west of the town of Custer. Other features noted
on the tour were clastic dikes, breccia pipes, and Mt. Rushmore National Monument.
After the final paper on Tuesday, the group discussed future plans.
Next years topic will be plate tectonics, at a site yet to be determined.
GRI Field Conference 1985
Anticipation and planning that had extended over three years came to
fruition as passengers boarded a Loma Linda University bus at the New Orleans Superdome 6
a.m., Monday, July 8. The 1985 Geoscience Research Institute Field Conference did not
begin formally until eight o'clock that evening at Keene, Texas, but since most of the
participants had been delegates to the General Conference Session, the field conference
group activities actually began in New Orleans. Participants who had not attended the
General Conference Session joined the touring group at Southwestern Adventist College in
Keene.
The field conference participants included five Geoscience Research
Institute staff members, seven resource persons from Southwestern Adventist College, Loma
Linda University, the E. G. White Estate, and private industry, and 22 invited
participants. The invited participants could be loosely classified as
"students"; some were enrolled to obtain university credit for the field
conference, and all had been assigned a pre-conference study program to develop a
background in geology as a preparation for the conference experience. In addition to the
individuals who have been enumerated, four wives had the privilege of accompanying their
husbands during the 30 days and approximately 4500 miles covered by the conference.
Overseas Participants
The 1985 G R I Field Conference was unique in that, with two exceptions, all invited participants were from outside North America. These participants had been designated by the various world division committees of the General Conference of Seventh-day Adventists to serve as coordinators and resource persons for handling within their respective divisions the responses of the church to questions regarding the relationship between modern scientific viewpoints and the data given through revelation. They included college administrators and teachers, and administrators from union conference and division offices. Fourteen countries and eight colleges outside North America were represented.
Southwestern
The conference began with three days of orientation and lectures at Southwestern Adventist College, including a field trip to the Paluxy River fossil footprint site near Glen Rose, Texas. The last four days were given to lectures on the La Sierra campus of Loma Linda University. Travel during the conference included significant geological features in the states of Texas, New Mexico, Colorado, Wyoming, Montana, Utah and Arizona. A public address system in the bus provided for geological comments regarding the passing countryside, mini-lectures using charts for visual aids, and extended discussion while en route between stops. Formal lectures requiring projection facilities were given in motel conference rooms and churches at overnight stop locations. The three Sabbaths during the tour were spent at Carlsbad, New Mexico; West Yellowstone, Montana; and Moab, Utah.
Short Walks
Relief from the confines of the bus was provided by numerous short
walks to collect fossils or observe significant geological features, along with two major
hikes, one to the Specimen Creek fossil forest site in Yellowstone National Park, and one
to the Cambrian contact on the North Kaibab Trail in the Grand Canyon.
Some participants have a treasure of photographic mementoes of this
trip; all have a rich store of memories and a five centimeter thick notebook of resource
material covering the topics that were discussed during the conference.
The GRI in New Orleans
Four GRI staff scientists participated in the Ministerial Pre-session and were delegates to the General Conference Session held in New Orleans this last summer. Of the large number of seminars conducted during the Pre-session, the Science and Religion Seminar with over 490 in attendance was one of the most popular. Lectures and discussions on creation, flood geology, and age-dating methods were held.
Display Booth
For the first time since the establishment of the GRI in 1958, a display booth was erected and manned during the General Conference Session. Designed by Dr. Clyde Webster, the display attracted much attention. Under the heading, PIECING TOGETHER GOD'S DESIGN, large colorful puzzle pieces were mounted. Flanking this centerpiece were illustrated examples of research undertaken by the GRI staff that has aided in a better understanding of Earth's past history. In addition to disseminating useful information, the display gave GRI personnel opportunity to meet persons interested in creationism, to answer questions, and to engage in interesting discussions.
Geoscience Reports, Winter 1985/86 No. 6
Editor --- Clyde L. Webster
Associate Editor --- Katherine Ching
Subscription requests, correspondence, and notices of change of address should be sent to: Geoscience Reports, Geoscience Research Institute, Loma Linda University, Loma Linda, CA 92350.
Geoscience Reports is a newsletter published by the Geoscience Research Institute to present current happenings at the Institute as well as articles of general interest which deal with creation/evolution issues for primary and secondary school teachers. The views expressed are those of the authors and not necessarily those of the Institute.
Staff of the Institute are: Ariel A. Roth - Director, Robert H. Brown, Katherine Ching, Harold G. Coffin, L. Jim Gibson, and Clyde L. Webster.