Download The Truth About Alfred Wegner

The Truth About Alfred Wegner
My name is Ned Malone and I am a journalist. I have interviewed many great men in my
time. Professor Challenger, the great scientist who explored the Lost World. Captain
Nemo, amazing explorer of ocean depths. Charles Darwin, who some call the father of
modern biology. But none who have changed science the way Alfred Wegener has managed
to change science.
Born on November 1, 1880, Alfred Wegener earned a Ph.D in
astronomy from the University of Berlin in 1904. However, he
had always been interested in geophysics, and also became
fascinated with the developing fields of meteorology and
climatology. Wegener was also a tutor and professor at variou
s German universities.
In 1911, while at Marburg, Wegener was browsing in the
university library when he came across a scientific paper that
listed fossils of identical plants and animals found on opposite
sides of the Atlantic. Intrigued by this information, Wegener
began to look for, and find, more cases of similar organisms
separated by great oceans.
Orthodox science at the time explained such cases by
postulating that land bridges, now sunken, had once connected
far-flung continents. But Wegener noticed the close fit between the coastlines of Africa
and South America. Might the similarities among organisms be due, not to land bridges, but
to the continents having been joined together at one time? As he later wrote: "A
conviction of the fundamental soundness of the idea took root in my mind."
Such an insight, to be accepted, would require large amounts of supporting evidence.
Wegener continued to collect this evidence and in 1915 published The Origin of Continents
and Oceans, a book outlining his Theory of Continental Drift. In his book, he claimed that
about 300 million years ago the
continents had formed a single mass,
called Pangaea (from the Greek for "all
the Earth"). Pangaea had rifted, or split,
and its pieces had been moving away from
each other ever since. This meteorologist
was not the first to suggest that the
continents had once been connected, but
he was the first to present extensive
evidence from several fields.
As a non-geologist, Wegener's trespass into the discipline of geology was not welcomed. A
supporter later explained, of his problems in gaining a hearing: “To work on subjects which
fall outside the traditionally defined bounds of a science naturally exposes one to being
regarded with mistrust".
Throughout his career he
was an outsider in the field;
and although it gave him
the ability to see beyond
the entrenched ideas of
the science, it also opened
him to mistrust and
criticism. At that time,
scientists kept well within
the bounds of their own
specialties.
Not only did biologists keep
Artwork of Alfred Wegener discussing with
away from the earth
Dr Werner Janensch with a map and dinosaur
sciences, but even
skull on a table in front of them
geophysics, geology and
geography had been totally
separated, with no connection between these obviously-related disciplines or their
specialists. Wegener's work that reconnected them was derided throughout his lifetime,
and he himself was ostracized by the narrow geological community.
Reaction to Wegener's theory was almost uniformly hostile, and often exceptionally harsh
and scathing; Dr. Rollin T. Chamberlin of the University of Chicago said, "Wegener's
hypothesis in general is of the footloose type, in that it takes considerable liberty with
our globe, and is less bound by restrictions or tied down by awkward, ugly facts than most
of its rival theories."
Part of the problem was that Wegener had no convincing mechanism for how the
continents might move. Wegener thought that the continents were moving through the
earth's crust, like icebreakers plowing through ice sheets, and that centrifugal and tidal
forces were responsible for moving the continents. Opponents of continental drift noted
that plowing through oceanic crust would distort continents beyond recognition, and that
centrifugal and tidal forces were far too weak to move continents -- one scientist
calculated that a tidal force strong enough to move continents would cause the Earth to
stop rotating in less than one year.
Another problem was that flaws in Wegener's original data caused him to make some
incorrect and outlandish predictions: he suggested that North America and Europe were
moving apart at over 250 cm per year (about ten times the fastest rates seen today, and
about a hundred times faster than the measured rate for North America and Europe).
Indeed, there were scientists who supported Wegener: the South African geologist
Alexander Du Toit supported it as an explanation for the close similarity of strata and
fossils between Africa and South America, and the Swiss geologist Émile Argand saw
continental collisions as the best explanation for the folded and buckled strata that he
observed in the Swiss Alps.
Unfortunately, before his theory was ever fully accepted, Wegner died. Throughout his
studies, Wegner had made many trips to Greenland. Wegener made what was to be his last
expedition to Greenland in 1930. While returning from a rescue expedition that brought
food to a party of his colleagues camped in the middle of the Greenland icecap, he died, a
day or two after his fiftieth birthday.
Wegener's theory continued to find scattered support after his death, but the majority
of geologists continued to believe in static continents and land bridges.
Finally, in the 1950’s, increased exploration of the Earth’s crust and ocean floor revealed
that Wegner’s basic ideas were valid – the continents did move. However, so does the
crust of the ocean floor.
Alfred Wegner was a man who stretched the bounds of science. His theory was rejected
partially because in formulating it he had straying outside of the narrowly-defined field in
which he was expected to work. However, once accepted, that same theory broadened and
enriched many diverse fields, not only those of geophysics, geology, geography and
evolution, but also oceanography, biology and zoology.
PROFILE
Harry Hess: One of the Discoverers of
Seafloor Spreading
Harry Hess (1906–1969) in his World War II Naval uniform.
Photo courtesy of Princeton University, Department of
Geosciences.
Nothing could feel more solid than the ground under our feet.
Yet the surface of the Earth is not fixed, but rather broken up like a jigsaw puzzle into enormous
plates that move. This process is called plate tectonics, and it transformed the thinking of
geologists. One of them, Harry Hess, was an instrumental figure in figuring out how plate
tectonics worked.
Hess possessed two valuable skills: careful attention to detail and the ability to form sweeping
hypotheses. This unusual combination produced groundbreaking work on a number of subjects,
including the origin of ocean basins and island arcs, mountain building, and the movement of
continents. The idea that the continents might have moved, or “drifted” over time can be traced
back to the sixteenth century, when European cartographers compiled world maps based on the
seagoing expeditions of that time. This idea was transformed into the theory of “continental
drift” by German meteorologist Alfred Wegener in 1912, when he published a treatise with
several lines of supporting evidence that went beyond simply matching the continents like puzzle
pieces. These lines of evidence included, for example, matching geological formations and
paleontological distributions from South America and Africa. Wegener’s critics correctly pointed
out, however, that the continents could not simply “plow” though the ocean floor as Wegener
had vaguely theorized. It was Hess who determined how oceanic mountain ranges, called midocean ridges, are fundamental to the tectonic movement that results in the drift of continents.
According to his own account, Hess flunked his first course in mineralogy at Yale and was told
he had no future in the field. Nevertheless he stuck with it, and was teaching geology at
Princeton when World War II was declared. Already a lieutenant junior grade in the Naval
Reserve, Hess was called to active duty after Pearl Harbor and was eventually to rise to the rank
of Rear Admiral. He soon developed a system for estimating the daily positions of German Uboats in the North Atlantic, and requested duty aboard a decoy vessel in order to test the
program. It worked.
He then served as commander of the attack transport U.S. Cape Johnson in the Pacific Ocean,
taking part in major landings at Marianas, Leyte, Lingayen Gulf, and Iwo Jima. Ever the
scientist, while cruising from one battle to the next, Hess kept the transport’s sounding gear
(which bounced sound waves off the sea-floor in order to determine the underwater relief or
topography) running day and night. This led to his discovery of submerged and curiously flattopped mountains that he named “guyots” in honor of the Swiss founder of the Princeton
geology department. It also produced thousands of miles of echo-sounding surveys of the ocean
floor.
The postwar period was a revolutionary one for the earth sciences. Efforts to map the ocean floor
intensified, thanks in large part to the newly-created U.S. Office of Naval Research. Within a
few years, a curious terrain had emerged: vast, flat plains interrupted by ridges, or more
precisely, vast mountain ranges. In the Atlantic Ocean, the “ridge” is about midway between the
continents on either side, and thus it became known as a mid-ocean ridge. We now know that the
ocean ridge system snakes around the entire globe in a continuous chain some 80,000 kilometers
long. In 1953, scientists discovered that a prominent valley, called the Great Global Rift, ran
down the center of these ridges. Intrigued, Hess reexamined the data from a completely fresh,
unorthodox perspective. In 1962, he proposed a groundbreaking hypothesis that proved vitally
important in the development of plate tectonic theory. It addressed several geologic puzzles: If
the oceans have existed for at least 4 billion years, why has so little sediment accumulated on the
ocean floor? Why are fossils found in ocean sediments no more than 180 million years old? And
how do the continents move?
Hess theorized that the ocean floor is at most only a few hundred million years old, significantly
younger than the continents. This is how long it takes for molten rock to ooze up from
volcanically active mid-ocean ridges, spread sideways to create new seafloor, and disappear back
into the Earth’s deep interior at the ocean trenches. This “recycling” process, later named
“seafloor spreading,” carries off older sediment and fossils, and moves the continents as new
ocean crust spreads away from the ridges.
Supporting Wegener’s theory of continental drift, Hess explained how the once-joined continents
had separated into the seven that exist today. The continents don’t change dramatically or move
independently, but are transported by the shifting tectonic plates on which they rest. The theory
also explained Hess’s puzzling guyots. They are believed to be once-active volcanoes that rose
above the surface like modern-day island arcs and then were eroded to sea level. As the ocean
crust spread away from the higher ocean ridges, the guyots sank below sea level, becoming
completely submerged. Hess also theorized that because the continental crust was lighter, it
didn’t sink back into the deep earth at trenches as did the oceanic crust. Instead, it scraped rock
off the descending ocean crust and piled it into mountain rages at the trenches’ edge. Hess also
incorporated the idea proposed by Swiss geologist Emile Argand in the 1920s that mountain
belts are also created when two continents collide.
Hess’s bold intuition was subsequently corroborated. Later studies showed that the age of the
ocean floor increases with distance from the ridge crests, and seismic studies confirmed that the
oceanic crust was indeed sinking into the trenches. His report, History of Ocean Basins, was
formally published in 1962 and for some time was the single most referenced work in solid-earth
geophysics.
Hess also contributed significantly to his university, where he became head of the Princeton
geology department, and was an important member of the national scientific community. He
helped design the national space program, and was one of ten members of a panel appointed to
analyze rock samples brought back from the Moon by the Apollo 11 crew. He died in August,
1969, a month after Apollo 11’s successful mission. A National Academy of Sciences memoir
calls Hess “one of the truly remarkable earth scientists of this century.”