Re: Plate tectonics - Back to the FAQS

From: Bigdakine (bigdakine_at_aol.comGetaGrip)
Date: 01/30/05 

Date: 30 Jan 2005 21:48:37 GMT

>Subject: Re: Plate tectonics - Back to the FAQS
>From: "George" george@wtfiswrongwithyou.com
>Date: 1/29/05 10:13 PM Hawaiian Standard Time
>Message-id: <_G0Ld.26525$ox3.3773@attbi_s04>
>
>
>"Landy" <none@nowhere.com> wrote in message
>news:cth03k$22m$1@seagoon.newcastle.edu.au...
>>
>> "don findlay" <don@tower.net.au> wrote in message
>> news:1107012674.823933.211810@z14g2000cwz.googlegroups.com...
>>> Q1. Call it 'expanded' or 'growth' or whatever, ...what is the
>>> fundamental, last word, bottom line evidence that the Earth has got
>>> bigger?
>>>
>>> A1. The creation of the ocean floors. These amount to two thirds of
>>> the Earth's surface at the present time, and give us an indication of
>>> the order of magnitude of enlargement of the Earth. The abyssal hills,
>>> which provide the record of ocean floor growth are the most prolific
>>> (and least mentioned - within plate tectonics) structures of the ocean
>>> floors.
>>
>> I just can't help myself.....
>> So then why, Don, is there no ocean floor older than Jurassic? I could say
>> that you're forgetting (conveniently) that ocean floor is destroyed at the
>> same
>> rate it is created. But that would be like trying to argue evolution with
>a
>> creationist.
>>
>> So what's the answer Don? To deny that seafloor is destroyed by subduction
>> is to argue that there was no seafloor prior to the Jurassic and hence the
>> earth
>> had no oceans. In fact if you're arguing that the current area of oceans
>> represent
>> earth expansion since the Jurassic, the you're arguing by default that
>prior
>> to then
>> the earth was entirely continental crust.
>> cheers
>> Bill
>>
>
>Actually, Bill. There is, in point of fact, plenty of ocean floor that is
>older
>than Juassic. The thing that people keep forgetting is that a lot of the
>older
>ocean floor is no longer beneath the sea, but is now welded to the
>continents,
>or buried beneath them. I've got about 100 lbs of former ocean floor in my
>shed
>that ranges from 350 million to 1 billion years old.

I have a few chunks of the Fransican formation in my parent's flower bed.
Others in use as paper weights.

Oh, what an ignominious end for such old rocks.

  I've got a boulder of
>Devonian-aged ocean floor in my yard that is about 1,000 lbs. But I
>understand
>your point. The EEers keep whining that there are more spreading ridges than
>
>there are subduction zones, but fail to recognize that the subduction zones
>are
>subducting at a rate that is at least 5 to 6 times faster, on average, than
>the
>spreading ridges are spreading. The Indian plate is subducting at the
>location
>of the Sumatra trench at a rate of about 60 cm/yr, while the East Pacific

Whoops, I know thats wrong. Its 6cm/yr. However, in the Northern Tonga area
subdcution rates exceed 20cm/yr.

>rise
>spreads at a rate of about 11 cm/yr.

Which is abnormally fast. Average sea-floor spreading rate is ~3-4cm/yr while
average suduction rate is several times that.

Stuart
>
>
>
>
>
>
>
>

Dr. Stuart A. Weinstein
Ewa Beach Institute of Tectonics
"To err is human, but to really foul things up requires a creationist"
  

"Creationists aren't impervious to Logic: They're oblivious to it."