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CHAPTER 2.8 OTHER CONTINENTAL
QUESTIONS
There are some other aspects of continental
uplifting and movement that should be covered. That is the purpose of this
chapter.
INEVITABLE CONTINENT CLUMPING
The nature of subduction and the directional movement of new
continents pretty much guarantees that, over time, continents will inevitably
end up clumping together. They will subduct the oceanic plate in front of them
until they run into another continent.
However, new cosmic impacts can
cause the creation of new continents that will then inevitably clump together
through subduction.
Eurasia is, in effect, the graveyard of older,
clumped continents, drawn together over the eons.
CONTINENTS & TECTONIC PLATES
Some people have become understandably confused about the difference
between a continent and a tectonic plate. Sometimes they seem to be the same
thing.
sometimes not.
The Standard Theory isn't terribly useful
here. It just lists as continents the seven standard land masses that we are
taught in school and then shows a map of 12 primary tectonic plates, some of
which relate to a single continent and some of which don't. Closer examination
of the Earth's surface results in a whole series of mini-plates and
sliver-plates. The Standard Theory doesn't explain the relationship of
continents and tectonic plates
it is what it is.
The Theory of
Antipodal Impact Effects looks at the history of the continents and tectonic
plates and tries to make sense of the way that they move and change.
When a continent is first uplifted, it rides on its own tectonic plate.
The uplift frees it from most connection to other tectonic plates.
However, during the life of a continent, it can see many changes
relating to its condition as a solo player on its own tectonic plate. South
America and Africa are continents that survive today on their own tectonic
plates.
However, some continents smash together (usually the ocean
between them is subducted) and become a combined continent on a single tectonic
plate. Examples of this include North America (which is a mixture of at least
two continental masses) and Antarctica (Western Antarctica and Eastern
Antarctica). Each of these pairs of combined continents share a tectonic plate.
The mega-combined continent of Eurasia has several continental masses
(Siberia, India and many other continents that have been captured and absorbed
over the ages). Eurasia shares three major tectonic plates (the Eurasian plate,
the Indian plate and a little bit of the North American plate which controls
the eastern tail of Siberia, starting at the rift at lake Baikal).
The
poor Old Australian continent has been broken up into three different plates.
There is the top half of the Old Australian blob that is now in the Antarctica
plate (as Eastern Antarctica), the bottom half of the Old Australian blob in
the Australian plate and the shattered remains of the Australian tail in the
Philippines plate. One should also note that some of Australia's tail was
stolen by the Indian continent during its uplifting and is now in the Indian
plate.
Therefore, continents and plates start out as one and the
same thing. However, as time goes by, that can change.
WHAT DOES IT TAKE TO UPLIFT A
CONTINENT?
The Manacouagan impact 214 MYA, which caused a
minor extinction, should be compared to the non-extinction event (or minor
extinction event) related to the Chesapeake Bay crater 35.5 MYA.
I am
proposing that the impact object which caused the100 km diameter Manicouagan
crater 214 MYA in Canada also caused at least a large minor extinction event of
the same time period. I am proposing that this impact also created the small
continent of Western Antarctica, as well as lots of other nasty antipodal
impact effects.
However, just 35.5 MYA, an impact object created a 90
km diameter crater at Chesapeake Bay in Maryland (USA). The extinction graph
shown on Wikipedia indicates that there was only a minor extinction event
around that time (18% of genera extinguished in the large minor event versus
13% at 35 MYA).
How could two craters of almost the same size produce
such different results?
I believe that there were three factors which
led to the difference. These factors were:
1. SIZE A crater of 100km in diameter is
11% bigger than a crater of 90km in diameter. The area of the crater (which
would be directly related to the impact force) is a function of the square of
the diameter. Therefore, the force that produced a 100 km crater would have
been 23% greater than the force producing a 90 km crater. Furthermore, a crater
on hard rock with the same force will be somewhat smaller than a crater in
marshy ground. Therefore, the crater in Canada may indicate a force that was as
much as 40% greater than that at Chesapeake Bay.
2. SURFACE CONDITIONS
The Manicouagan crater was created right in the middle of a continental
mass, with no mitigating effects from water. The Chesapeake Bay impact occurred
at the seashore, where sand (remember Dunkirk) and water could have had some
minor mitigating effect.
3. ANTIPODE LOCATION The antipode of
the Manacouagan impact is hypothesized to be at the ocean floor
a
relatively thin area of the lithosphere. The antipode of the Chesapeake Bay
impact occurred under the mountains of Eastern Australia. The crust is much
thicker there and the mountains create even more weight and shear problems than
usual. The combination of these factors appear to be the
reason that the Manacouagan impact object (100 km crater) caused a large minor
extinction and uplifted a continent (albeit it a small one), while the
Chesapeake Bay impact object (90 km crater) did not uplift a continent, nor did
it have the same kind of extinction effect.
This comparison of factors
and the resulting Western Antarctica continent versus no continent also gives
us an idea of what kind of crater must be present to consider continental
uplift. It appears that a crater minimum of 100 km in diameter is needed for
continental uplift, but only if all of the conditions are right.
WHY SHOULD WE ASSUME THAT EXTINCTIONS ARE RELATED
TO COSMIC IMPACTS?
So, let's see where we are.
We
now have pretty solid evidence for all three of the most recent major mass
extinctions
1. End-Cretaceous 65 MYA
2. Triassic 202
MYA
3. Permian 250 MYA We have no evidence for the
other three older major extinctions.
Why should we assume that cosmic
impacts and their antipodal impact effects were the cause of these other three
extinctions? There are three reasons.
For the first reason, let's look
at the explanations given for those three other, older major extinctions by the
Standard Theory:
1. Cambrian Extinction Glacial Cooling or
Oxygen Depletion
2. Ordovician Extinction Glaciation and Sea
Level Lowering
3. Devonian Extinction Glaciation or Meteorite
Impact All of these three explanations are also the logical
consequences of a large cosmic impact with devastating antipodal impact
effects. The volcanism created by the antipodal impact effects will fill the
air with ash and sulfurous fumes for thousands of years. Major glaciation is
the expected result. Therefore, glaciation is merely a result of the antipodal
impact effects, just as antipodal impact effects are merely a result of a large
cosmic impact on-or-near-land. Furthermore, sea level lowering is just a result
of major glaciation, which is, again, an expected antipodal result of a large
cosmic impact .
The point is that a large cosmic impact would explain
all of the other causes that have been named.
This brings us to the
second reason that we should believe that cosmic impacts were the reason for
the three older major extinctions. That reason is: Statistics.
As
detailed in earlier, we would expect that there would be between six to eight
impacts on-or-near-land that would be big enough to create major extinctions
during the past 510 million years. We have experienced six major extinctions.
We have a clear path to the understanding of how the most recent three of these
extinctions were due to cosmic impacts.
We know that we have a dynamic
planet that hides ancient evidence. Do we really believe that we only had two
or three big impacts on-or-near-land in the last 510 million years instead of
six to eight? Do we really believe that the Moon (which showed lots of major
impacts) was just really unlucky and the Earth was really lucky?
Unlikely. It's much more likely that the evidence of ancient major
cosmic impacts is too old to find easily. As we get better at modeling the
ancient world (i.e. getting India in the right place, etc), we may be able to
better pick up clues relating to these older impacts and their antipodal
uplifts and hotspots.
The third reason that we should believe that
cosmic impacts were the reason for the three older major extinctions is the
pattern of major and minor impacts and major and minor mass extinctions.
This book deals primarily with the major mass extinctions and the major
cosmic impacts.
However, there are many more minor (but significant)
mass extinctions and many more minor (but significant) cosmic impacts. The
pattern of major and minor mass extinctions is very much in line with the
pattern of major and minor cosmic impacts.
During the last 500 million
years, there have been 32 confirmed impact craters on earth of 20 km diameter
or more. There are likely many more craters of this size that have not yet been
discovered (due to erosion, subduction, etc.). 17
During this
same time period, there have been six major mass extinctions and many more
minor extinctions. More than 98% of all species that have ever lived are now
extinct. 33
Why should we have to invoke "rare mantle plumes"
and arbitrary glaciation when the pattern of cosmic impacts and their antipodal
effects will explain extinction events just as well
especially now that
we have the "smoking gun" for the last three big ones?
BLOBS WITH TAILS
If I am
going to create a theory that says that the antipodal impact effects of a very
large cosmic impact will cause the formation of uplifted continents in the
shape of "a blob with a tail", then I should be prepared to produce examples of
this condition.
Furthermore, I should be prepared to explain shapes
that do not meet the criteria I have described.
On the one hand,
someone could argue that, with enough leeway, a person could argue for any
continental shapes that he might come up with
especially in a
combination continent. Furthermore, a "blob with a tail" is a pretty elastic
geological structure. A lot of different variations can fit into that model.
However, we don't end up with any blobs with two or three tails. There
are no hourglass blobs. And we don't come up with any with no tails (at least
not without a solid explanation i.e. Australia and Eastern Antarctica),
except for the combination continent of Asia and the
very-tricky-but-finally-explained continent of North America.
Reality
is messy. Not every continent is going to have a perfect "blob with a tail"
form. But the form will still be clearly identifiable.
First, I should
note that the definition of a continent includes the area of the continental
shelf, not just the area that happens to be above sea level at this moment in
time.
South America is the prototypical blob with a tail. Not all
continents are going to be as clear an example of this structure. But South
America exemplifies the look.
Africa is another fairly easy example of
a blob with a tail. However, the blob looks rather flattened
until we
remember that part of the African plate is on top of the Matterhorn in the
French Alps (as famously illustrated in a documentary shown on the History
channel). The African plate (and, in this case, the continent) extends up
through the Mediterranean Sea into the southern part of Europe, itself. It also
includes the Arabian Peninsula. Once this is understood, the blob shape is more
what we would expect.
Actually, we also have to consider the shape of
Africa along with the part of Africa that was uplifted and separated into South
America. Not all of South America came from Africa. The west coast of South
America came from the ocean floor, which is why we have so many ancient sea
life fossils found in the Andes.
COMBINATION CONTINENTS
Now
we come to combination continents. North America is a combination continent
with at least three separate continental tectonic plates involved, as explained
in Chapter 2.5.
Antarctica is another combination continent. It
consists of a relatively new, small western blob with a tail and a larger,
older eastern "half-blob" that separated from the original Australian
continent. As the Standard Theory notes, the northern section of Eastern
Antarctica fits right into the Great Australian Bight, where it used to be
joined.
Australia is a shattered continent. Half of its blob is now
Eastern Antarctica. Part of its tail was stolen by the rise of India and the
rest of its scattered tail consists of the islands between Australia and
Indochina, except for the Indonesian islands (which is an island arc formed by
the Chicxulub antipode's hotspot).
This leaves us with Eurasia, which
is a mega-combination continent. It not only contains the Indian continent and
the Siberian continents, but it also contains the folded remains of many other
continents. In many ways, Eurasia is the graveyard of old continents, as they
are swept up by the subduction process and aggregated over time into this
amorphous monster continent.
THE BASICS OF IMPACTS &
CONTINENTS
Most of the continental masses are so old that
clues about their formation are going to be very difficult to uncover. However,
there are several suppositions that we can make about the continents and the
impacts that caused them.
These are:
1. CONTINENTAL FORMATION Continents are
created at the antipodes of really big cosmic impacts, not through some other
process.
2. CONTINENTAL SHAPE Continents are created in the
shape of "a blob with a tail" by the directional hydraulic pressure exerted by
a mantle plume caused by a really big cosmic impact.
3. CONTINENTAL
LOCATION - Continents are formed at and near the antipode of a really big
cosmic impact, with the "blob" being centered just beyond the antipode.
4. CONTINENTAL COMBINATION Continents tend to clump together as
a result of the "subduction machine" which gradually subducts the ocean between
them until they combine.
5. CONTINENTAL BREAK UP Combination
continents stay together until they are torn apart by impact effects, as we see
in the cases of Old Australia, South America and Eastern North America.
However, the subduction machine will eventually bring things back together.
6. CREATION AND DESTRUCTION Continents have been created and
destroyed over the billions of years of the existence of the Earth. In just the
last 250 million years, we have seen
a. India created
b. Australia broken
apart
c. Siberia created
d. Siberia starting to be pulled apart
with the rift at Lake Baikal
e. India and Siberia smashing into Eurasia
and adding to the size of that landmass
f. Western Antarctica created
g. Western Antarctica moving to combine with Eastern Antarctica
(formerly part of Australia)
h. Eastern North America created
i. South America created Imagine the continental creation
and destruction that preceded these events, back when cosmic impacts were even
more prevalent.
7. IMPACTS HAVE DIMINISHED Impacts are not as
big or as frequent as in the history of the early Earth, but they are still big
enough to wipe out the entire human race.
8. REGULAR IMPACTS The
history of major and minor cosmic impacts (32 confirmed Earth craters of more
than 20 km in size in the past 500 million years 17 ) shows that
impacts have not gone away. They keep coming back.
Michael
Rampino of New York University developed a theory called the Shiva Hypothesis
to explain the continued assault of cosmic objects on the Earth and the other
solar system planets.
The Shiva Hypothesis
"says that gravitational disturbances caused by
the Solar System crossing the plane of the Milky Way galaxy are enough to
disturb comets in the Oort cloud surrounding the solar system. This sends
comets in towards the inner Solar System, which raises the chance of an impact.
According to the hypothesis, this results in the Earth experiencing large
impact events about every 30 million years (such as the Cretaceous - Tertiary
extinction event).
However, mass extinctions do not show any
(statistically significant) periodicity." 23 Even
though the Shiva Hypothesis doesn't stand up to strict statistical analysis,
this problem could easily be explained by random variation of the orbits of
perturbed comets and meteors. The cause could be happening every 30 million
years, just like clockwork, but the results might appear random due to the huge
variation in the paths of the agents.
Furthermore, the sample size of
major extinctions (six) is extraordinarily small. It is difficult to expect
much statistical confirmation from a sample size this small. And expanding the
criteria to include minor extinctions just adds more uncertainty in data (i.e.
We can't be sure that the Triassic extinction was even an extinction, so what
kind of doubts will there be about minor extinctions? Also, we are finding new
big and small craters all the time
the completeness of this project is
far from finished).
The Shiva Hypothesis is quite appealing. But, even
if it is wrong, we are still left with a continuing geological history of
impacts (major and minor) and mass extinctions (major and minor).
OTHER POSSIBLE IMPACT, LIP & HOTSPOT
CONNECTIONS
With the exception of the CAMP, I look at LIPs
as the likely initial location of a hotspot that is antipodal to a large
impact. There are two of these that cry out for further investigation.
A. The Kerguelen Plateau
B. The Columbia River
LIP THE KERGUELEN PLATEAU
The Kerguelen Plateau is a LIP (Large Igneous Province) that is located just to
the north of Antarctica and at approximately the same longitude as India.
The hotspot beneath the Kerguelen Plateau has been moving from the
southwest to the northeast. The earliest activity was around 120 MYA. The most
recent activity in the northeast is around 35 MYA. 78,79,80
While none of the sources cited above lists an antipodal impact as a
possible cause of the hotspot (should we be surprised?), I believe an antipodal
hotspot is the cause.
Furthermore, I believe that there is a telltale
physical feature that was located antipodal to the hotspots beginning
location 120 MYA. This feature is Hudson Bay in Canada.
The shape of
Hudson Bay is strikingly reminiscent of the shape of the Gulf of Mexico and the
Yucatan Peninsula.
Others have looked at the rounded area near the
bottom of the bay and have found no sign of a crater. However, the Gulf of
Mexico does not have a crater near its rounded areas. The Chicxulub crater is
at the top of the thumb.
I suspect that there is a crater
near the top of Hudson Bay on one side or the other that relates to the
Kerguelen Plateau.
COLUMBIA RIVER LIP
The
Columbia River LIP is located in and near Oregon and Washington State. It
occurred about 16 MYA.
I view this LIP as the large initial eruption of
a hotspot. However, I believe that the hotspot involved is the Yellowstone
hotspot, the second biggest super volcano in the world.
The Columbia
River LIP does not match up with the path of the Yellowstone hotspot. It is too
far to the north. However, if the original hotspot happened to be located under
the heavy weight of the Rocky Mountains, the basalt lava flows could have
leaked out to the north, rather than coming up right at the antipode.
I believe that if someone does the research, they will find a large crater in
the South Pacific somewhat antipodal to the 16 MYA extrapolated position of the
Yellowstone hotspot. After allowing for domal uplift, it will probably turn out
that the impact occurred around 24 MYA.
THE CARIBBEAN LARGE IGNEOUS
PROVINCE
After putting together the scenario for South
America and then North America, I realized that the Caribbean LIP (Large
Igneous Province) could be explained, also. I had originally believed that this
explanation was beyond the information that I possessed.
The Caribbean
Plate sits between the North American Plate and the South American Plate. The
Caribbean Plate is awash with volcanism, which is called the Caribbean LIP.
There is significant controversy surrounding the formation of the
Caribbean LIP and its unusual turning movement. One theory says that the region
was formed over the Galapagos hotspot and moved to its present location.
Another theory says that the Caribbean Plate and its LIP is the result of
interaction with North America and South America, although the mechanism is
rather fuzzy 103 .
An analysis of the timing involved helps
to clarify the situation. While the LIP was formed approximately 139 MYA to 69
MYA 104 , the dominant phase of this activity occurred 94 MYA to 85
MYA 105.
When we combine this information with the fact that
the New England Seamount Chain stopped 82 MYA and the Laramide Orogeny (Rocky
Mountain building) began 80 MYA to 70 MYA (see Chapter 2.5), a mechanism
becomes clearer.
The fact that the new Eastern North American Continent
was pulling away to the north and the west since its inception 202 MYA, would
have led to an ocean floor spreading at its southern border.
132 MYA,
the uplift of the South American Continent would have absorbed some of the
older volcanic output in its Amazonas craton LIP (see Chapter 2.4).
Subsequent volcanic output from spreading would accrete to an area
north of South America, and, because South America was moving west, this area
could be twisted into its own plate, especially when the Eastern North American
started to move in a different direction around 80 MYA (see Chapter 2.5).
Somewhere around 80 MYA, the Eastern North American Plate encountered
the tail of the north and westward moving tail end of the Siberian Plate and
rotated clockwise, bringing the tail of the Eastern North American Continent
somewhat to the south, gradually killing the ocean floor spreading and then
twisting (and possibly creating) the Caribbean Plate. 119
The
Chicxulub impact 65 MYA would have augmented this North American plate move to
the South, firmly ending the Caribbean LIP formation. More movement to the
south by the Eastern North American Continent would have occurred 35 MYA due to
the Chesapeake Bay impact, causing more rotational movement by the Caribbean
Plate.
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