Dear Lin,
The last time I wrote in to the group was back in late May, 2013, as I was getting heavily involved in the busy season for our businesses. Things have calmed down and I can devote some time to proper responses to the several questions that were raised about my theory of extinction level volcanism at the antipode of a very large impact.
Just a suggestion:
In recent years, several other craters of around the same age as Chicxulub have been discovered, all between latitudes 20°N and 70°N. Examples include the disputed Silverpit crater in the North Sea and the Boltysh crater in Ukraine. Both are much smaller than Chicxulub, but are likely to have been caused by objects many tens of metres across striking the Earth. This has led to the hypothesis that the Chicxulub impact may have been only one of several impacts that happened nearly at the same time. Another possible crater thought to have been formed at the same time is the larger Shiva crater, although the structure's status as a crater is contested.
Silverpit crater If one assumes the meteor impact theory is right, the size of the crater can be combined with assumptions about the speed of an impacting object to estimate the size of the impactor itself. Impacting objects are generally moving at speeds of the order of 20–50 km/s, and at these speeds an object about 120 m (393 feet) across and with a mass of 2.0×109 kg would be required to form a Silverpit-sized crater, if the object was rocky. If it had been a comet, the crater would have been larger.
For comparison, the object which struck the Earth at Chicxulub is estimated to have measured approximately 9.6 km (6 miles) across, while the object responsible for the Tunguska event in 1908 is thought to have been a comet or asteroid about 60 m (196 feet) across, with a mass of about 4×108 kg.[12]
Boltysh Crater is located in central Ukraine, in the basin of the Tiasmyn River, a tributary of the Dnieper River. It is 24 kilometres (15 mi) in diameter, and is surrounded by an ejecta blanket of breccia preserved over an area of 6,500 square kilometres (2,500 sq mi). It is estimated that immediately after the impact, ejecta covered an area of 25,000 square kilometres (9,700 sq mi) to a depth of 1 metre (3.3 ft) or greater, and was some 600 metres (2,000 ft) deep at the crater rim.
The crater contains a central uplift about 6 kilometres (3.7 mi) in diameter, rising about 550 metres (1,800 ft) above the base level of the crater. This uplift currently lies beneath about 500 metres (1,600 ft) of sediment deposited since the impact, and was discovered in the 1960s during oil shale deposits exploration.
The Deccan Traps are a large igneous province located on the Deccan Plateau of west-central India (between 17°–24°N, 73°–74°E) and one of the largest volcanic features on Earth. They consist of multiple layers of solidified flood basalt that together are more than 2,000 m (6,562 ft) thick and cover an area of 500,000 km2 (193,051 sq mi) and a volume of 512,000 km3 (123,000 cu mi). The term "trap", used in geology for such rock formations, is derived from the Swedish word for stairs[1] and refers to the step-like hills forming the landscape of the region. There are some who suggest that an impact of sufficient speed and size could have blasted through the earths crust and into magma that in turn bled up onto the land.
The Shiva crater is a another huge impact crater located under the Arabian Sea off the coast of India near Bombay. This crater also dates from the K-T boundary, 65 million years ago, when the Chicxulub crater at the tip of the Yucatán Peninsula also formed. Although it has shifted because of sea floor spreading, when pieced together it would be about 370 miles (600 km) by 280 miles (450 km) across and 7.5 miles (12 km) deep (and may be just part of a larger crater). It is estimated to have been made by a bolide (an asteroid or meteoroid) 25 miles (40 km) in diameter.
All of these have been contested (???) as if there is a concerted effort to keep impact from being the cause, but perhaps to be considered anyway.
B.R.S.
The discussion last spring was positively Rumsfeldian for me. I found out that there were several things that I didn't know that I didn't know. Of course, finding these things out was a major purpose in contacting the group, so that was a good thing.
The major things that I didn't know that I didn't know were:
1. SIMA VS. SIAL — I didn't know that the surface of the Earth was composed of two different types of material, with the lighter continents floating higher than the heavier basaltic material. I had assumed it basically all the same stuff, rather than being differentiated. (thanks, EMAN)
2. LIQUID MANTLE — I found out that the mantle isn't really liquid in the ordinary sense. Rather, it is more like wet cement. It's only liquid in reference to a geological time scale. For all intents and purposes, it acts more like its solid. (thanks, ChuckB)
3. TRAPPED EXTRUSION — I found out that the impact from a six-mile-in-diameter rock (the Chicxulub impact object) was not nearly big enough to force extrusion of material at the antipode of impact. I found that my mechanism for trapped extrusion (as in the cold heading business) would only work in the case of a much, much bigger impact (because the cold heading trapped extrusion process is a near field phenomenon). (Thanks, ChuckB)
4. RAPID SURFACE MOVEMENT — I found out that I could not have continents "pinwheel around" into position in a way that would be much too fast for them to get there (specifically my movement explanation for Western Antarctica). (Thanks, EMAN)
All of these factors have to be integrated into my theory if my theory is to make any sense. And, mostly, they can.
But, I think that there is an even bigger issue involved here. And that issue is the question: "Why is Ben even bothering to pursue this theory when so many of the premises have been proven wrong?"
I believe that it is legitimate for members of the group to wonder why discussion of this theory is not unlike trying to answer the question: How many angels can dance on the head of a pin?
First, you have to show some evidence of the existence of angels before anyone is going to take you seriously. Unlike the angel question, I actually do have some evidence to present for the case of extinction level volcanism at the antipode of a very large impact. The evidence is statistical.
The initial statistical evidence was the very reason that I started looking at this possibility in the first place. In an informal way, I asked myself this question about the Chicxulub impact and the Deccan traps: What are the odds that the largest (by far) impact of the past 100 million years would occur at virtually the same time as the largest (by far) igneous province eruption of the past 100 million years?
As I examined impacts and possibilities of antipodal volcanism, I found more statistical evidence. The odds these were random, unrelated coincidences grew smaller and smaller.
During the summer and fall of this year, I approached this statistical question in an even more organized and methodical way. I will present my findings in the next email.
The reason that I did not bring up the statistical question to begin with was due to the fact that I had not developed it fully and because I didn't think that it was necessary. I thought that I had a theory that worked, that was internally consistent and that fit the facts. Why bother with the reason why I began looking into the matter to begin with?
At this point, I believe that it is important to share the mounting evidence of statistical improbability that large impacts and antipodal volcanism are unrelated.
But, even if I present a convincing statistical case for extinction level volcanism at the antipode of a very large impact, that will not be enough. Without a viable mechanism for this activity to occur, the theory will be ignored. As Alfred Wegener found out, evidence without a convincing mechanism does not win the day.
Will I be doomed to wander the earth in search of a mechanism until I die in a blizzard in Greenland? Not an appealing prospect. Not even a posthumously commemorative song by the Amoeba People is likely to relieve the bitterness of unrequited vindication.
So, my second email will present a revised mechanism. This mechanism will actually conform to geological reality. I promise to do this without relying on Ancient Aliens, Cryptozoology or even a Sharknado Apocalypse. However, I may need to invoke the wisdom of that eminent musical geologist, Elvis Presley.
And, of course, I will be looking for comments.
After I get through these first two detailed emails, I will address the other questions that have been posed, as well as some interesting additions. These include:
1. EMAN's question about rapid surface movement.
2. Lin's question asking why the Indonesian island chain isn't just a convergent subduction zone as opposed to being a hotspot trail leading to a mantle plume at Lake Toba in northern Sumatra.
3. The creation of the moon.
4. Explaining India's rapid movement during its journey to a crash landing in Asia, as compared to the significantly slower movement of other tectonic plates.
Is this ambitious enough?
Regards,
Ben Fishler
__._,_.___
Your email settings: Individual Email|Traditional
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe
__,_._,___
No comments:
Post a Comment