Questions for Uniformitarianists

[otseng]

Uniformitarianism is one of the most important unifying concepts in the geosciences. This concept developed in the late 1700s, suggests that catastrophic processes were not responsible for the landforms that existed on the Earth's surface. This idea was diametrically opposed to the ideas of that time period which were based on a biblical interpretation of the history of the Earth. Instead, the theory of uniformitarianism suggested that the landscape developed over long periods of time through a variety of slow geologic and geomorphic processes.

The term uniformitarianism was first used in 1832 by William Whewell, a University of Cambridge scholar, to present an alternative explanation for the origin of the Earth. The prevailing view at that time was that the Earth was created through supernatural means and had been affected by a series of catastrophic events such as the biblical Flood. This theory is called catastrophism.

Source: PhysicalGeography.net

Uniformitarianism is a geological doctrine. It states that current geologic processes, occurring at the same rates observed today, in the same manner, account for all of Earth's geological features. Thus, it assumes that geological processes are essentially unchanged today from those of the unobservable past, and that there have been no cataclysmic events in earth's history. As present processes are thought to explain all past events, the Uniformitarian slogan is, "the present is the key to the past."

Source: Uniformitarianism.net

Some questions for uniformitarianists:
Why are there distinct lines between the sedimentary layers?
Why are they parallel to each other?
How did the stratas get formed?
Where did all the material come from to form the stratas?
Where do we see evidence of stratas being formed now?
Why do the majority of faults split through multiple layers?
Why do sedimentary stratas generally start in the Cambrian layer? Why are there none before that?
Do sedimentary layers exist older than 500 MYA?
Why are there little to none sedimentary stratas on top of shields (exposed cratons)?
Why are there relatively little sediments on the ocean floors near the ridges?
Why are there gaps in time in the stratas?
If those layers got eroded away, how did it happen?

[YEC]

Recumbent folds in layers of strata indicate that the strata was still soft when folded.
Think about it...if the rocks were hard...they would snap, crackle and pop....not bent in half.

I think the uniformatarian model needs some work.

Recumbent folds, or any other folds for that matter, don't indicate soft sediment deformation. The folds formed at depth, where temperature and pressure are greater than at the surface. Rocks deform differently at high pressure and temperature than they do under surface conditions.

Here's my favorite piece of evidence that folded rocks weren't soft:

Those folds occur in mountains, and while the mountains were being formed (and therefore while the folds were being formed) clasts of rock (like river cobbles) were being eroded from them.

http://www.talkorigins.org/faqs/lewis/#strength

This is a clear indication that the folded rocks were hard. How are you going to erode river cobbles from layers of loose mud and sand?

Your problem is explaining the folds at or near the surface that were not formed at depth.

[John S]

It would appear to me that if a layer was deposited slowly with a different sediment composition, weathering processes would at the same time affect the current exposed layer. This would cause a more gradual delineation between the two layers. If there were no weathering process to affect the base layer so that no sediments from the base layer could move and mix with the new layer, I can see how a a slow sedimentation might cause distinct lines. Another problem is that not only are lines generally distinct, but they are parallel to each other for large sections of land. I cannot see how a slow process can achieve this.

If the deposition were occurring on land, or if the sediments were exposed after they were originally deposited in water, then weathering will play a role. If this happens a soil horizon, called a paleosol, may form. I’m a little hesitant to bring these up since they’re starting to veer off topic, but I do think they’re worth mentioning. These are pretty common in the rock record. They’re tough to reconcile with the idea that most/all of the rock record is the result of a single, year-long event. If all of the rock record was deposited in a year, then how did the paleosols form?

A web page that discusses paleosols (their recognition and a little about their distribution) and their relation to Flood geology is here:
http://home.entouch.net/dmd/paleosol.htm

After going off on that brief tangent, I’ll move on to a more relevant point. The layering (planarity and areal extent) in the Grand Canyon area isn’t different from modern sedimentary deposits. In my original post I linked to a seismic image of young deposits in Puget Sound:

ACTIVE TECTONICS OF THE SEATTLE FAULT AND CENTRAL PUGET SOUND, WASHINGTON — IMPLICATIONS FOR EARTHQUAKE HAZARDS
http://earthquake.usgs.gov/regional/pac ... fig7f.html

Compare that image to the images in this paper from another part of the Colorado Plateau (I tried to find something online that was closer to the Grand Canyon, but I couldn’t – the same formations occur in this part of Utah):

Geophysical Surveys of the Upheaval Dome Impact Structure, Canyonlands National Park, Utah
http://www.seismo.unr.edu/ftp/pub/louie ... ction.html

The nature of sedimentary bedding in older rocks (like the Mesozoic and Paleozoic rocks in the Colorado Plateau) isn’t different from the type of bedding seen in younger (including modern) rocks.
The sedimentary bedding in the rock record (including the Grand Canyon area) isn’t composed of perfectly parallel beds with sharp contacts – bedding thickness changes (beds get thicker or taper out), the composition of rocks changes laterally (a formation can become sandier or shalier, for example), unconformities occur (which in the Grand Canyon area can have a surface relief of 10’s of feet), and so on. I think it’s a mistake to use local surface exposures (even very impressive ones like the Grand Canyon) to make generalizations about the entire rock record. I’ve got a book that’s got stratigraphic sections (formations, their thickness and composition, etc.) for a good part of the Colorado Plateau area. If you’re interested I’ll some of the relevant figures and post them. The American Association of Petroleum Geologists (http://www.aapg.org) puts out a series of geologic highway maps that include stratigraphic sections. Their map of the Southern Rocky Mountains covers the Grand Canyon and the rest of the Colorado Plateau. I think they may have some cross sections too, but I can’t remember for certain.

Another question this brings up is what exactly causes changes in depositional material? For instance, in the Grand Canyon, we see layers that are hundreds of feet thick each spanning millions of years. So, for millions of years, one particular type of sedimentation was deposited. Then it abruptly (relatively speaking) changes to another depositional material and that was layed down for another several million years. What would cause these changes? And why was only one type of sedimentation able to be deposited for millions of years? Why millions of years instead of say, thousands, or decades of years?

Changes in depositional material are caused by some of the processes I listed earlier. If sea level changes, the type of sediment being deposited changes. If the source of sediment changes (if a river changes course, for example), then the type of sediment being deposited changes. Ocean currents could change, which would disrupt the supply of nutrients to microorganisms, which would affect limestone formation.

There certainly can be changes in sedimentation on the order of thousands of years or younger. There’s nothing that requires changes to be slow (on the order of millions of years). You can see these changes in the rock record – for example there may be changes in the types of clay minerals in a shale reflecting different sediment sources. There may be a layer of sand deposited by a storm. Sedimentary rock formations (with few exception) aren’t composed of thick layers of homogeneous sediments.

Here is the problem, if sedimentary layers are formed by water, why do we have sedimentary layers at practically every place on the land surface? If it is formed underwater, would it then not be expected to see more sedimentary layers underwater that on the land? This is actually the opposite of what we see.

I think the trouble here may be thinking that sedimentary rocks that are currently on land were always on land. A lot of the rocks at the Grand Canyon, for example, were deposited underwater (a lot of the shales and limestones for example, plus some of the sandstones). The modern configuration of the land surface hasn’t been steady throughout the history of the earth. Sediments that were deposited underwater can be uplifted and exposed as sea level changes and as continents move (and collide and break apart, etc.).

Could you provide some examples of deposits forming in deserts?

Gladly. My favorite it the Navajo Sandstone of the Colorado Plateau (which goes by the name Aztec sandstone in Nevada and Nugget sandstone in Wyoming).

Navajo sandstone in Zion National Park:
http://protophoto.com/picture.html?pic=5466

An example of characteristic eolian (wind related) cross bedding in the Navajo:
http://geoimages.berkeley.edu/GeoImages ... une14.html

Modern eolian deposits at White Sands, New Mexico (Note that the links to the figures within the text don’t work, but the figures are shown at the bottom of the page)
http://www2.nature.nps.gov/geology/park ... ystems.htm

Explanation of eolian (windblown desert deposits)
http://pubs.usgs.gov/gip/deserts/eolian/

[John S]

Your problem is explaining the folds at or near the surface that were not formed at depth.

Large recumbent folds, like the ones you mentioned, aren’t shallow folds, so the factors I mentioned (heat and pressure increasing with depth) are still valid. Another important factor that influences whether rocks bend or break is strain rate (as Jose pointed out in an earlier response). If rocks are strained slowly they will bend, while if they are strained quickly they will break (this is true for other materials too, like rulers or floor joists).

More important than discussing the factors that control the deformation behavior of rocks is the evidence that rocks weren’t “still soft” when folded. You haven’t addressed the evidence I presented (synorogenic conglomerates) that rocks weren’t soft when they were folded. In order to support your contention that folds in rocks imply soft sediments you need to respond to the points I raised that very clearly indicate otherwise.

[YEC]

John S,
Your post didn't even seem to mention recumbent folds.....what was your point?

[John S]

John S,
Your post didn't even seem to mention recumbent folds.....what was your point?

From my post of February 10:

"Recumbent folds, or any other folds for that matter, don't indicate soft sediment deformation. The folds formed at depth, where temperature and pressure are greater than at the surface. Rocks deform differently at high pressure and temperature than they do under surface conditions."

That paragraph was also quoted by you in your response of March 17.

From my post of March 17:

"Large recumbent folds, like the ones you mentioned, aren’t shallow folds, so the factors I mentioned (heat and pressure increasing with depth) are still valid. Another important factor that influences whether rocks bend or break is strain rate (as Jose pointed out in an earlier response). If rocks are strained slowly they will bend, while if they are strained quickly they will break (this is true for other materials too, like rulers or floor joists)."

Not only did I mention recumbent folds, those were the first words of both of my responses. As to what my original point was, you highlighted it in red in your response of March 17 to me.

[YEC]

John S......Once again there are many recumbent fold that are found at the tops of mountains that were NEVER under the deep down buried pressure you mentioned.


interesting photo page

[John S]

John S......Once again there are many recumbent fold that are found at the tops of mountains that were NEVER under the deep down buried pressure you mentioned.

I’m going to start with the caveat that none of what I’m about to present is central to the argument about whether or not folds in rocks indicate soft sediment deformation. I’ve already presented evidence in the form of synorogenic conglomerates, that indicate that rocks in fold and thrust belts (which is where folds, recumbent and otherwise, shallow or deep, occur) were fully lithified when they were deformed. As I’ve mentioned twice now (and as Jose mentioned in a post last month) strain rate is also very important. Low strain rates favor bending while high strain rates favor breaking. When you’re dealing with folds in sedimentary rocks, which are very common in fold and thrust belts, then strain rate is very important. When you’re dealing with folds in metamorphic rocks (which is where a lot of the impressive mountain-scale recumbent folds occur), it’s less important. I should have made this distinction in my original post.

Before you try to discount strain rate, you ought to know that there are many active folds in fold and thrust belts around the world. As an example, a M 6.7 earthquake in 1983 and a M 5.5 earthquake in 1985 occurred along a blind thrust fault in central California. The Cenozoic fault, which involves Quaternary through Cretaceous formations, is overlain by a fault-bend anticline. There’s additional evidence that the fold didn’t form in soft sediments. While this folding was occurring, quaternary conglomerates were being deposited. This indicates the rocks those conglomerates were being derived from (which include some of the same Tertiary formations as in the fold) were fully lithified.

Reference:
Namson, J. S., and Davis, T. L., Seismically active fold and thrust belt in the San Joaquin Valley, central California. 1988. Geological Society of America Bulletin, 100, 257-273.

There are many other active folds in California, and there are more in places like Taiwan and China (near the Himalayas). There are many studies that use geodesy (mainly GPS) to measure the rates of deformation in these areas. To use another example from California:

Shortening and thickening of metropolitan Los Angeles measured and inferred by using geodesy. By Donald F. Argus, Michael B. Heflin, Andrea Donnellan, Frank H.Webb, Danan Dong, Kenneth J. Hurst, David C. Jefferson, Gregory A. Lyzenga, Michael M.Watkins, James F. Zumberge, published in 1999 in Geology, v. 27, 703-706.


With that said I’ll move on to your post. I think we need more than a cartoon drawing to go on. From your cartoon you seem to be implying that recumbent folds form at the surface (correct me if I’m wrong), and that’s just not correct. Why are you claiming that features found on tops of mountains weren’t buried to great depth? Features found at the tops of mountains, or perhaps more accurately the rocks that comprise the tops of mountains, are the rocks that have been uplifted the most in that mountain range. That means those rocks (and the folds and faults that developed in those rocks) formed deeper in the crust than the lower parts of the mountains, which haven’t been uplifted as much. Here are a few examples:


From the Swiss Alps:

BURKHARD, M. and GOY- EGGENBERGER, D., 2001, Near vertical iso- illite- crystallinity surfaces cross-cut the recumbent fold structure of the Morcles nappe, Swiss Alps. Clay Minerals 36, 159-170.

The metamorphic rocks involved in this fold here were exposed to temperatures >300 degrees C. That indicates a depth of very roughly 12 km (with a geothermal gradient of 25 degrees C/km). An online description of the Morcles nappe is here: http://earth.leeds.ac.uk/subalps/morcles_nappe.htm

A lot of the folds in the link you titled “interesting photo page” at the bottom of your last post (http://earth.leeds.ac.uk/folds/picturegallery.htm) formed under similar conditions. 12 (and possibly more) of 37 folds are in metamorphic rock

From the Canadian Rockies:

Cook, D. G. , 1973. Structural Style influenced by lithofacies, Rocky Mountain Main Ranges, Alberta-British Columbia. Geological Survey of Canada Bulletin 233, 73p.

One of the folds described there occurs near a place called Ogre Peak in Cambrian rocks. The fold there is 1000+ ft tall. They describe other folds that have amplitudes up to 4,500 ft. The thrust sheets, of which these folds are a part, are 10,000 + ft (~ 3 km) thick. That’s the minimum burial depth.

You can form folds in shallower rocks (take a look at the references I provided about active folds), and you can form some pretty tight folds like chevron folds (shown in several of the pictures in the website you linked to) if you fold a thinly-bedded rock (like the shale-sand sequences mentioned in that same website).

However, as I said at the beginning of this post, most of this discussion is irrelevant since regardless of the depth at which folds form there is evidence that the rocks involved were lithified.

[YEC]

John S, you are filtering your science through frafulent evo-minded eyes.

Try folding a rock...they snap crackle and pop.

The soft sediment is the best answer.

[John S]

Hi Otseng,

I’ve put together a more detailed description of the occurrence of Precambrian sedimentary rocks in North America. I’ve tried to use references that are available online so you can get more information. The links to the papers and abstracts I cite are provided in the references section.

I’ve tired to provide brief descriptions of the types of sedimentary rocks that occur in the basins, as well as a bit of information about their depositional environments. If you’d like more information about particular aspects of the basins please ask.

A lot of the basins I describe formed in rift basins. These develop when continents begin to break apart, and later develop into oceans. The oldest rocks in these basins are often sandstones (of a variety called arkose), which are derived from rocks the adjacent to the rift depression, and volcanic rocks like basalt. As the rift develops into an ocean these rocks are overlain by marine rocks like sandstones, shales, and carbonates (limestone, etc.).

Basins also develop adjacent to mountains. As mountains are uplifted they are eroded, and as the material derived from these mountains accumulates, basins form. You can see examples of these in modern mountain chains like the Rockies, and you can see them in older mountain chains like the Appalachians. Remnants of them are also preserved for even older mountains that have been so eroded that no topographic highs are left (like the Grenville mountains in eastern North America).

All of the Precambrian basins I discuss below contain layered sedimentary rock, often tens of thousands of feet. Because of this I don’t think it’s possible to maintain that the first occurrence of layered sedimentary rock marks the beginning of Noah’s Flood. I’m working on a post the describes younger (Quaternary) sedimentary basins, and I’ll try to post that in the next few days. I’ve mentioned before that modern sediments are also composed of layered sequences. That’s another very strong indication that layered sedimentary rocks can’t be the fingerprint of Noah’s Flood.

A worthwhile discussion for a later date would be the features contained within sedimentary rocks (Precambrian and otherwise) that indicate they weren’t deposited as a whole in the span of a year. I mention a few of these features below, but I’ll leave off bringing them up in detail for now.

Montana, Alberta, and British Columbia

I mentioned the Belt Supergroup in an earlier post. It’s composed of a thick (up to ~10 km/ 33,000 ft) clastic sedimentary rocks (like shale and sandstones, some of which have been lightly metamorphosed) and carbonates (like limestone). It formed in the late Precambrian (~740 Ma and older) when the supercontinent Rodinia (http://www.clas.ufl.edu/users/jmeert/rod.jpg) broke apart. It’s part of a related series of rift-related sedimentary basins that formed at that time in what is now western North America. Price and Sears (2000) provide a good description of what the basin looked like when it formed. Their entire paper is available online in PDF format.

The rocks of the Belt Supergroup are very photogenically exposed in Glacier National Park. The geology is briefly described by the National Park Service here: http://www2.nature.nps.gov/geology/parks/glac/

They show photos of features like mud cracks and ripples that are preserved in some shaley formations. These features are an indication that at least part of the formation was deposited in a shallow water environment, and the mud cracks indicate it periodically dried out.

Utah

I mentioned the Uinta Group (also called the Uinta Mountain group) before too. It’s composed of a thick (7 km/23,000 ft+) sequence of sedimentary rocks including feldspar-rich sandstone (called arkose) and siltstone. It’s related to the rifting of Rodinia as well, and these sediments were deposited in a failed rift called an aulacogen. Sears et al. (1982) have a good description of this. The abstract is available online.

Another series of Precambrian sedimentary rocks in the Big Cottonwood Group, which is exposed in the Salt Lake area. It’s composed of a 4 km+ (13,000 ft) thick series of sandstones and shales that were deposited ~900 Ma. The oldest known tidal rythmites (cyclic variations in the clay-rich rocks associated with tides) are preserved in these rocks. That means that variations in sedimentation that occurred at a timescale of less than a day are preserved. These are described in Ehlers and Chan (1999). The abstract of their paper is available online.

Another Precambrian sedimentary sequence that is exposed in Utah and southern Idaho is the Brigham Group, which is composed of sandstones, shales and carbonates that have been lightly metamorphosed, but that still preserve sedimentary features like bedding. These rocks are well-exposed in the mountains of northern Utah and southern Idaho. A brief description of part of this group is given by Link et al. (2002), which is available online.

Eastern North America

Following the Grenville Orogeny (an episode of mountain building that occurred in the Late Precambrian that I mentioned in an earlier post), which marks the assembly of Rodinia, rifting in what is now eastern North America resulted in the formation of the Iapetus Ocean (a precursor to the Atlantic Ocean that closed during the mountain building events that created the Appalachian Mountains in the Paleozoic Era). The opening of Iapetus was initiated in the very late Precambrian and continued into the early Cambrian. This rift basin is filled with sedimentary rocks (sandstones and shales), volcaniclastic, and volcanic rocks (like basalts). A brief description is given here:
http://tanasi.gg.utk.edu/GGT/ggt20/plateau.html

The authors of that site also talk about the Paleozoic tectonic history of that area as well, which involves the formation of other sedimentary basins, but since I’m limiting this post to the Precambrian I’ll omit that part for now.

Texas Panhandle (Smith et al., 2002; Smith 2002)

Geophysical techniques (like seismic reflection) and limited drilling indicate that a sedimentary basin formed under part of the Texas Panhandle in the Precambrian (~1.1 Ga). The basin is filled with volcaniclastic rocks (http://volcanology.geol.ucsb.edu/frags.htm ) which include ash-fall tuffs which form as ash from an eruption settles out of the air) and ash-flow tuffs which form as very hot material from an eruption flows along the ground surface and metasedimentary rocks.

Older Precambrian sedimentary rocks

There are remnants of older Precambrian sedimentary basins (2 billion years +), but the rocks involved have been metamorphosed into rocks like quartzite (derived from sandstones), schist and gneiss (derived from shales and other mudrocks) and marble (derived from carbonates). Although sedimentary features like bedding aren’t preserved in the schists and gneisses their chemistry provides a clue to their origin. They contain minerals that are rich in aluminum (like some garnets, kyanite, and so on). An explanation of the changes in mineralogy that accompany metamorphism can be found here: http://geology.csupomona.edu/alert/meta ... gional.htm

That site also describes how variations in the minerals in a set of metamorphic rocks can be used to track metamorphic grade (or the degree of metamorphism).

References

Ehlers, T. A., and Chan, M. A., 1999. Tidal sedimentology and estuarine deposition of the Proterozoic Big Cottonwood Formation, Utah. Journal of Sedimentary Research 69, 1169-1180.
http://jsedres.geoscienceworld.org/cgi/ ... /69/6/1169

Link, P. K., Corsetti, F. A., and Lorentz, N. J., 2002. Siliciclastic-carbonate cycles of the Neoproterozoic Blackrock Canyon limestone, southeastern Idaho. Geological Society of America Abstracts with Programs, v. 34.
http://gsa.confex.com/gsa/2002RM/finalp ... _34209.htm

Price, R.A. and Sears, J.W., 2000. A preliminary palinspastic map of the Mesoproteroiz Belt-Purcell Supergroup, Canada and USA: Implications for the tectonic setting and structural evolution of the Purcell anticlinorium and the Sullivan deposit; Chapter 5 in The Geological Environment of the Sullivan Deposit, British Columbia, (ed.) J.W. Lydon, T. Höy, J.F. Slack, and M.E. Knapp; Geological Association of Canada, Mineral Deposits Division, Special Publication No. 1, p.61-81.
http://geol.queensu.ca/people/price/pdf ... Sears).PDF

Sears, J. W., Graff, P. J., and Holden, G. S. 1982. Tectonic evolution of lower Proterozoic rocks, Uinta Mountains, Utah and Colorado. Geological Society of America Bulletin 93, 990–997.
http://www.gsajournals.org/gsaonline/?r ... 2.0.CO%3B2

Smith, Diana E., Miller, Kate C., Keller, G. Randy, 2002. Delineation of the Precambrian Hereford Basin: An integrated geophysical study of an ancient basin within the basement of the Texas Panhandle. Geological Society of America Abstracts with Programs, v. 34.
http://gsa.confex.com/gsa/2002SC/finalp ... _32930.htm

Smith, Diana E. 2002. Integrated Geophysical Study of the Precambrian Basement of the Texas Panhandle Region. Masters thesis abstract.
http://www.geo.utep.edu/pub/ladewig/Gra ... smithd.pdf

[otseng]

The fault line goes through multiple stratas, all the way to the top. This is commonly what we see in faults.

Going "all the way to the top" of an exposure, like the fault in the quarry face that you linked to, is very different than a fault cutting through Cambrian through modern rocks.

You're not justified in saying that because the fault cuts all of the rocks in a cliff or a quarry face, that those faults cut through rocks of Cambrian to modern age.

My point is not that it has to cut through the Cambrian layer per se. That strata might not even exist in that locality. My point is that we should see an abundance of faults where at one strata on down, there is evidence of a fault. But at that point on up, there should be no evidence of a fault. If U15m is true, this should be abundant in the rock record.

Your thought experiment sounds reasonable to me, and your "uniformitarian" style of faulting is what is observed. There are faults that cut rocks no older than Cambrian, just as there are faults that cut rocks no older than Ordovician (and so on for every other geologic period).

Could you provide some pictures to help me see what you are presenting?

There are faults that cut through Precambrian to modern rocks, but that doesn't indicate anything unusual. All that means is that the fault was active in modern times (like the San Andreas).

And if U15m is true, faults that do not cut through modern rocks, but do cut through old rocks should be common.

It is true that there are a lot of metamorphic Precambrian rocks, but not all Precambrian rocks are metamorphic. The links you provide can't be used to represent the Precambrian as a whole, they're brief descriptions of local geology.

From the wikipedia, "The sedimentary rock cover of the continents of the Earth's crust is extensive, but the total contribution of sedimentary rocks is estimated to be only five percent of the total. As such, the sedimentary sequences we see represent only a thin veneer over a crust consisting mainly of igneous and metamorphic rocks." From this, 95% of the rock total is not sedimentary rock. And practically all of it is a "thin veneer" on the surface. Sure, some sedimentary layers can be found below the Cambrian layer, but it is the exception. So, the question is, why only a "thin veneer"?

Jose offers this explanation:

However, as previously mentioned, they are often referred to as metamorphic rock, rather than sedimentary, because of the time and pressure that has enabled them to metamorphose--from shale to slate, from limestone to marble, etc. The layers are still there, even if the crystal structure of the rock has been changed by compression.

If the metamorphic rock was once sedimentary, what exactly caused the transformation? How exactly does time and pressure cause sedimentary rock to become metamorphic rock? If one uses the general explanation of time, pressure (and heat) to form metamorphic rock, how does that cause sedimentary layers to become a rock with no evidence of any layers in the metamorphic rock?