RightWingGirl said:
Nvxplorer--Thanks! I've go to go now, but could I take you up on that sometime? I should be on tomorrow GMT -8. 7:15
OC1--A toxic environment in which two fish were living?
Thank you all for your insight and comments!
Gidday RWG,
I have been noticing an exchange between yourself and several others on this board, concerning the nature of the Himalayas and how sea shells could get to the top of the mountains.
As with others in this thread, I am no geologist. Nor am I a scientist. However there are many good mainstream geology books around which describe the process as it is currently understood.
One thing needs to be pointed out. These text books are distilled and summary versions of what can be found in the technical scientific literature. To write the technical scientific literature, people have to go into the field and collect data to support their arguments. Hence it is the quality of that data which is so important to the interpretation placed upon it.
What I am about to give you is an explanation offered in Understanding Earth by Frank Press and Raymond Siever (3rd ed). It represents the conventional explanation.
1) You need to imagine an earth some 60 million years ago when the plate upon which India sat began to interact with the plate upon which Tibet sat. India was hundreds of km away from Tibet then. Dont be alarmed at my figure of 60 million years it can be measured using radio isotope dating. We have plenty of direct and indirect evidence that the earth is 4.6 billion years old. This is roughly 80 times as long as 60 million years. We also know (from direct measurements) that continents can move 1, 2, 3, or 4 cm a year. In 60 million years, the Indian plate would have traveled 60,000,000 x 1 cm = 60,000,000 cm. Now this equals (60,000,000 cm / 100,000 cm/km), 600 km at 1 cm/year, or 1200 km at 2 cm/year. It equals 1800 km at 3 cm/year.
2) Now imagine India approaching Tibet at 1, 2 or 3 cm/year, and it is 600km to 1200 km away! What happens to the ocean floor between the two continents? Remember that the ocean floor has sediment continually being loaded onto it. But this sediment also buries sediments from millions of years before. Well all of this begins to get squeezed. As the distance between the continents closes, some of the squeezed sediments gets pushed up, while some goes under the Tibetan continent.
3) As the closure continues, to the point of contact, the sediments mud, shells and all go up, and up and up as the Himalayas grow.
4) Today, India is still ramming northward into Tibet (and earthquakes occur). This can be measured. Furthermore the Himalayas are growing that is they are popping up more than they are being eroded away. This too can be measured. Again, look at the calculations. If the Himalayas have been pushed up by (let me be very rash) an average of 0.2mm/year for the last 60,000,000 years (this is the net rise or uplift minus erosion) then they would have risen 12 km!
5) The result is ocean sediments and other sediments sitting perhaps 12km above where they were deposited!
Now the above is a very simplified explanation of what the text book offered which was itself a very simplified version of what most geologists think happened after doing lots of field work. Not all geologists would agree. However, most who disagree would accept this description in broad principle.
Geologists think that it happened this way because they do the experiments which confirm this.
Do you see how this concept of sea floor being squeezed between two colliding continents can explain the occurrence of sea shells high up in the Himalayas?
If you can, get hold of some mainstream geology books. They should, if they are good ones, give you an idea of what we think and why we think that way. By why we think that way I mean that the books should either directly inform you of the data which demonstrates what is being claimed or they should give you plenty of references which will allow you to check it out.
Regards, Roland