----- Original Message -----
From: "Adam Crowl" <qraal@hotmail.com>
> Hi ASA
>
> I think one of the most annoying things about Creationist rhetoric is the
> way it confuses the appearance of a phyla, regardless of how "primitive"
the
> initial examples might be, with the modern article. Like Phyla have not
> evolved over time - as palaeontologists have been aware since last
century.
You are correct that the family, genera and species of the Cambrian phyla
are totally different from those alive today and this is something that is
entirely overlooked by many apologetical organizations. On my web page I
have the fish genera by period. Note that none of the living genera exist
prior to the Jurassic.
youngest period # Fish genera # living genera # extinct genera
Recent 3245 3245 0
Pleistocene 422 408 14
Pliocene 416 372 44
Miocene 496 320 176
Oligocene 321 207 114
Eocene 398 157 241
Paleocene 124 53 71
Cretaceous 340 38 302
Jurassic 146 5 141
Triassic 175 0 175
Permian 86 0 86
Pennsylvanian 106 0 106
Mississippian 163 0 163
Devonian 524 0 524
Silurian 57 0
57
Ordovician 5 0 5
Cambrian 1 0 1
But apologetical messups from RTB go on and on. in the same issue of
Connections, Hugh Ross has an article that says that the atmospheric
composition is finely tuned by the rates of subduction. He says:
"As more and more of the sun's fuel (hydrogen) ignites, the sun glows
brighter and brighter. At the same time, heat-trapping gases in Earth's
atmosphere (carbon dioxide and water vapor) get transferred, by organisms,
fromthe atmosphere to the crust. IN this amazing 'double coincidence,'
Earth's decreased heat trapping efficiency exactly compensates for increased
solar brightness so that EArth's surface temperature remains ideal for life.
"For some time scientists have been aware that this cycle demands
fine-tuned balancing fo erosion rates, plate tectonic activity, volcanic
activity, and, of course, the quantity and kinds of life on the planet
through time. The most recent research reveals in addition, the delicacy
ofthe rate at which Earth's crust plates, particularly the ocean-floor crust
plates, move beneath or 'subduct,' below the plates they collide with." Hugh
Ross, "Earth's Carefully Crafted Crust," Connections 1st qtr 2000, p. 2
He then says:
"Again, research produced a bonus. It just so happens that a dehydration
process at work in the downward-moving slabs leads to production of a talc
layer that both lowers and stabilizes the sliding friction of adjoinging
tectonic plates. This friction reduction and stabilization lowers the
earthquake risk to advanced life.
"The more we learn about what is required to keep life goiing for the
past 3.86 billion years, the more evidence we see that a Supernature shaped
nature."Hugh Ross, "Earth's Carefully Crafted Crust," Connections 1st qtr
2000, p. 2
The only article he cites is Stephen H. Kirby, "Taking the Temperature of
Slabs", Nature 403(2000):31-34. Reading that article there is no mention
whatsoever of the sun, atmospheric composition or the removal of greenhouse
gases from the atmosphere to the crust. Indeed, subduction really has
little to do with the scrubbing of the atmsophere of greenhouse gases like
CO2. Here is a tabulation of the CO2 content of the atmosphere through
geologic time. The first number is the age (millions of years ago) and the
second number is the amount of CO2 in the atmosphere compared to the present
day atmosphere. The present atmosphere is 1 on this scale.
co2 in atmosphere
myr 1=present atsosphere
570 5.28
560 6.52
550 7.24
540 10.60
530 13.96
520 17.82
510 16.16
500 14.37
490 14.11
480 14.00
470 14.53
460 15.04
450 14.24
440 13.43
430 12.78
420 11.83
410 10.68
400 9.09
390 8.10
380 9.14
370 10.11
360 9.85
350 8.51
340 3.54
330 1.78
320 1.25
310 1.01
300 0.90
290 0.94
280 0.91
270 1.07
260 1.26
250 1.34
240 1.49
230 1.66
220 2.11
210 2.15
200 2.06
190 2.02
180 2.10
170 2.18
160 2.25
150 2.15
140 1.82
130 2.19
120 2.20
110 2.07
100 1.78
90 1.63
80 1.58
70 1.41
60 1.26
50 1.27
40 1.19
30 1.13
20 1.12
10 1.02
0 .97
Robert A. Berner, "A Model for Atmospheric CO2 over Phanerozoic Time,"
American Journal of Science, 291(1991):339-376, p. 371
While the sun is believed to have simply increased in brightness throughout
geologic time, one can immediately see that the atmospheric CO2 in the late
precambrian (570 myr ago) was 5 times the present level which then increased
to almost 18 times the present value by 520 million years ago. The
plummeting value of CO2 in the atmosphere between 350 myr ago and 320
million years ago concerns NOT subduction but the rise of the coal swamps
and the massive burial of organic carbon in the form of peat which occurred
at that time. Fine-tuning has nothing to do with it.
By 270 myr ago when the atmospheric CO2 was about at present levels, the
earth began to freeze again as glaciers covered large parts of the earth.
The volcanism associated with the breakup of Pangea which began at 250 myr
ago and continued and increased through the Cretaceous pumped lots of CO2
into the atmosphere which caused the content to rise to around twice the
present level. (see Robert A. Berner Geocarb II, American Journal of Science
294(1994):56-91 esp. p. 71 fig. 3)
About 50 million years ago, the CO2Curve takes a dive. This is due to the
rise of the Tibetan plateau. It is the most effective CO2 scrubber in
today's atmosphere. Raymo and Rudman state:
"On the basis of these and similar observations, we propose that late
Cenozoic uplift of the Himalayan region and Tibetan plateau would have
resulted in regionally, and hence globally higher chemical erosion rates,
causing a drawdown of atmospheric CO2 and global cooling. The timing of this
tectonically driven CO2 decrease should be post-Eocene, coincident with the
formation of the Tibetan plateau and in agreement with geological evidence
for when global cooling was most rapid." M. E. Raymo and W. F. Ruddiman,
"Tectonic forcing of Late Cenozoic Climate," Nature, 359(1992):117-122, p.
119
**
"Over the past 700 Myr, only two other time periods were characterized by
Tibetan-size plateaux, the late Precambrian and the late Palaeozoic; these
were also intervals of widespread continental glaciation. IN summary,
despite the continuous presence throughout geological history of high
mountain terrain along the convergent margins of the world, it may be the
rarer occurrence of plateaux that can drive climate away from steady state
and decouple rates of horizontal and vertical tectonic movement."
"We propose that over the past 40 Myr, uplift of the Tibetan plateau has
resulted in stronger deflections of the atmospheric jet stream, more intense
monsoonal circulation, increased rainfall on the front slopes of Himalayas,
greater rates of chemical weathering and, ultimately, lower atmospheric CO2
concentrations. These changes in climate may initiate strong positive
feedbacks to global cooling through glacier-driven erosion." M. E. Raymo and
W. F. Ruddiman, "Tectonic forcing of Late Cenozoic Climate," Nature,
359(1992):117-122, p. 122
In short, the entire idea that continental subduction is responsible for the
atmospheric CO2 content is not borne out by the data of geology. The CO2
levels of the atmosphere over the past 600 myr has stumbled around like a
drunken sailor. The sun's brightness on the other hand, has increased
linearly over time. The atmospheric CO2 mechanisms show little sign of the
fine-tuning that Ross imagines.
I do wish christian apologists would do a better job of understanding the
complexities of the field they are writing about.
glenn
Foundation, Fall and Flood
Adam, Apes and Anthropology
http://www.flash.net/~mortongr/dmd.htm
Lots of information on creation/evolution
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