To Jon Harshman -- re geological column

This is in answer to John Harshman's bafflement over my last post in
response to his mention of the lithification of rocks. He has used
terms like:

"I really don't understand what you're trying to say here."

"I have no idea how you arrived at this scenario."

"You misunderstand something. Not sure what."

"I have no idea what scenario you're trying to promote."

Let me try again.

The geological column purports to show the history of the earth as
recorded in the rock types of the earth's outer crust. The label of
"era" covers those periods of time in which the various stages of the
development of life forms are understood to be reflected through the
fossils found in the layers. And the name "period" is used to denote
a span of time within the eras.

With me so far?

Okay. I wanted to know, from an evolutionary point of view, what
life would have been like if we had the ability to travel back in time
and observe living conditions during these periods and eras.
Following are a couple of versions of the time line:

http://www.sdnhm.org/exhibits/mystery/fg_timeline.html

http://www.bestcrystals.com/timeline.html

http://gallery.in-tch.com/~earthhistory/geologic%20timepage.html

http://www.talkorigins.org/origins/geo_timeline.html

http://en.wikipedia.org/wiki/Geologic_timescale

Start with Cambrian. This period of time ranges from 35 to 41 to 50
to 100 million years, depending on the writer, but, hey, what's a few
million here or there when you have billions to choose from.

So, for somewhere between 35 million to 100 million years, here we
are, living happily among the algae, worms, and jellyfish. We're not
sure how we sprang into existence full-fledged, but thankfully, we
exist.

Apparently, during this Cambrian period, we are living under water,
right? Shallow seas, according to the first link above.

One day sediment is deposited, probably through a flash flood that
washes sediment into the sea, and this sudden influx fossilizes my
neighbor, the trilobite, where he lies there in his freshly made,
unlithified bed. What happens to this layer during the millions of
years before another layer is laid down? And as more layers are laid
down, are they continuously under water, or do they emerge as dry land
for millions of years before being submerged again?

Here are my problems that I would like you to solve, if you can:
Shallow oceans cannot be a source of lithification. There's just not
enough pressure. It takes thousands of meters of sediment before the
lowest sediment begins to lithify. See:

http://www.priweb.org/ed/pgws/backyard/spindletop/spindletop_oil.html

So count water pressure out.

How about nearby land that has continuously eroded over millions of
years in such quantity that it builds up sufficient pressure to
lithify the resting place of the fossils? We would need a few
thousand meters of sediment from the land. But since shallow seas are
not a few thousand meters deep, I would expect that after a few
million years of deposition, land would be rising out of the sea above
my trilobite friend's head.

But since erosion occurs at a rate of 5 to 10 feet per year, see:

http://www.glo.state.tx.us/coastal/erosion/erosionrates.html

then the few thousand feet of land would erode away completely long
before the layers that are deemed to be from a later period are
deposited. (Indeed, come to think of it, if the rates of erosion were
applied to present-day topography, Mt. Everest should have long since
disappeared. Is there a reason why it hasn't? The rate of uplift
versus the rate of erosion doesn't answer this.)

So I would like a scientific, step-by-step explanation of how rocks
lithify over millions of years, considering that it is supposed to
have taken millions of years for layers to be laid down, and in face
of erosion rates.

Also, since most rocks are sedimentary rock, the layers seen in
canyons must have been covered by waterr. Can you explain how canyons
form through river-cutting, when their layers have been lying under
water for millions of years? Take the Grand Canyon, for instance. Is
this what the area looked like at one time before the canyon formed?

----------------------------------------------- ->water
_______________________________
_______________________________->rock layers
_______________________________
_______________________________

How does a river go about cutting a canyon in a setting like this?
For starters, the rocks are under water. Second, the Colorado River
would have to have been between 8 and 16 miles wide to create the
gorge that we see today. How would such a river operate through
shallow oceans?

And if you say that the topmost layer emerged as dry land before a
river began to do its work, do you have a mechanism for getting rid of
the water?

Here, I'll offer one.

A massive earthquake, in which land dropped away and allowed the water
to drain off.

------------- ------------------- ->water
__________\ / ____________
___________ \ / ______________
____________ \ / _______________
______________\_________________
\
------------- ->Colorado River now runs

Under this scenario, there's no need to propose millions of years of
river-cutting and slow uplift to create a canyon.

I await your better explanation.

.

Relevant Pages

  • Re: Meaning of the Geological Column
    ... |>>> and say that there are several places where one can find deposits, ... Do you understand that when we say Devonian, ... |>>layers of different rock types that have been designated as Devonian? ... |>>could be missing in a period but not all the rocks from that period. ...
    (talk.origins)
  • Re: Meaning of the Geological Column
    ... layers to lithify lower layers? ... there must have been deposition above any layers that were ... Remember that the rocks both left and right of ... contain the types of fossils that generally, in succesion, span life ...
    (talk.origins)
  • Re: Meaning of the Geological Column
    ... I don't understand what you mean by "some rocks from EACH period" are ... You can't do that worldwide for all layers. ... and across oceans if the continents in question were ... index fossils all range around a certain level of ...
    (talk.origins)
  • Re: Meaning of the Geological Column
    ... layers to lithify lower layers? ... There's a lot of places where rocks just lie there without any significant ... contain the types of fossils that generally, in succesion, span life ... something to do with evolution. ...
    (talk.origins)
  • Re: To Jon Harshman -- re geological column
    ... lowest sediment begins to lithify. ... So count water pressure out. ... of the sediments here are so new, ... they have not had the chance to turn into rocks - they ...
    (talk.origins)