Previous posts in the series:
- On the Grand Canyon and the Flood (1)
- On the Grand Canyon and the Flood (2)
- On the Grand Canyon and the Flood (3)
- On the Grand Canyon and the Flood (4)
- On the Grand Canyon and the Flood (5)
- On the Grand Canyon and the Flood (6)
- On the Grand Canyon and the Flood (7)
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The Grand Canyon, Monument to an Ancient Earth: Can Noah’s Flood Explain the Grand Canyon?
By Gregg Davidson, Joel Duff, David Elliott, Tim Helble, Carol Hill, Stephen Moshier, Wayne Ranney, Ralph Stearley, Bryan Tapp, Roger Wiens, and Ken Wolgemuth.
Chapter 17 — How Old is the Grand Canyon seems like a topic that has already been discussed. However, the preceding chapters talked about how old the rock layers were based on the relative laws of deposition and radiometric dating. What this chapter talks about is when those rock layers were eroded to form the canyon. In other words, we aren’t dating the rocks, we are dating the hole in the rock.
So we know the canyon has to be younger than the rocks that it cuts through. At the rim we have the Kaibab Formation about 270 million years old. But even younger rock layers compose the Grand Staircase that had to be deposited, hardened, and cut through before the rocks of the Kaibab and older underlying layers were eroded. Geologists studying the Grand Staircase know that the evidence of the regional uplift means the oldest possible age of the Grand Canyon would be 80 million years. And there the agreement ends, there is active debate currently among geologists whether the Grand Canyon was incised beginning 6 million years ago, or whether there was incision of a paleo-canyon long before that.
At the heart of the controversy is when did the Colorado River cut its way through the Kaibab Arch. The Kaibab Arch is no minor feature; it represents uplift of 3,000 feet above the surrounding region. Water does not flow uphill, so how did the Colorado River manage to cut through such an impressive topographic high point? Two of the authors/editors of this book, Carol Hill and Wayne Ranney, are in the thick of this debate.
Scenario 1 is shown in Figure 17-3. The up folded layers are the Kaibab Arch. The diagrams represent increasing time from A to D. Streams to the west and east of the Kaibab uplift were initially separate stream systems as shown in A and B. Arrows show the direction of flow. The Kaibab Arch was a drainage divide. The stream on the west would be cutting downward and cutting eastward into the arch by headward erosion. The headward erosion would have eventually breached the divide and connected with the stream to the east and diverting it to the west. This is a commonly observed phenomenon today known as the process of stream piracy.
Carol Hill is one of a small number of geologists who have rappelled down or climbed up the vertical canyon walls to explore and study caves in the limestone formations. She has studied and radiometrically dated speleothems (e.g. stalactites and stalagmites) in those caves. Hill and her colleagues have been able to determine when the ancient water table began to drop in elevation as the western canyon was cutting downward. Her controversial theory is shown in Scenario 2 in Figure 17-5.
She has argued that subterranean drainage networks formed in the limestone under the arch. As those networks worked their way eastward they eventually were able to intercept the eastern stream via sinkholes and swallow holes to create flow westward underneath the Kaibab Arch; as process known as karst piracy. Collapse of overlying rocks into the caves eventually opened up a surface passage through which the river could flow through the uplift. As the book says (page 175):
This scenario may sound far-fetched to those not familiar with cave processes, but this very phenomenon can be observed today in places like southwestern Germany. In the region of the Swabian Alb, water from the Danube River- flowing eastward toward the Black Sea- suddenly disappears down sinkholes, travels over 7 miles through caves, passes under a high ridge, and reappears on the other side to discharge the pirated water into the Rhine River and then north into the North Sea.
As a matter of fact your humble blog author’s specialty is Karst Hydrogeology. I was mentored by the late great James F. Quinlan as his assistant at Mammoth Cave National Park. Under his tutelage, I was able to study many examples of karst piracy in the Mammoth Cave region. While working on remediating Superfund sites near Bloomington, Indiana for a major corporation; I formulated a hypothesis that waste material dumped in a stream channel caused pirating to the springs on the other side of the ridge. It was necessary for the company to operate a treatment plant to treat the contamination in the springs. I hypothesized that by removing the waste, sealing the sinkholes, and restoring the previous surface drainage; a majority of the contamination at the springs could be reduced. The company, with EPA and state approval, did just that and it worked; contamination has dropped below detection limits at the springs.
So I favor Carol’s hypothesis; but time, and additional evidence will tell. And that is the point made by the book in the closing parts of this chapter. YEC often point out arguments between conventional geologist as “proof” that their theories are based on flimsy evidence and wishful thinking (YEC- an irony free community ☺). But argument and evidence, more argument and counter-evidence is exactly how real science works. And in the process everyone’s understanding increases. When someone points out data that contradicts your hypothesis, you must then modify your hypothesis to take the new data into account. The idea that you start with a conclusion, then shoehorn the data to fit the conclusion and ignore or arm-wave the data contradicting your conclusion isn’t science: it’s anti-science. I’ll let the book have the last word (page 177):
“For the Grand Canyon, there is broad agreement and a high degree of certainty on the timing and history of each rock layer’s formation, with oldest rocks dating back roughly halfway through the Earth’s 4.5-billion-year history. Our understanding of exactly how these layers were carved to form the Grand Canyon is a work in progress, though much has been learned in the last 50 years – and all if it is increasingly at odds with the flood geology model.”
Chapter 18 — Life in the Canyon: Packrats, Pollen, and Giant Sloths looks at the plants and animals that began to occupy the canyon as it formed, with particular evidence in what’s preserved in cave deposits. Caves found today represent the most recent ones to be opened and inhabited; older caves would have been eroded away.
The white-throated woodrat (Neotoma albigula) is commonly known as the packrat. They live in nooks and crannies that contain not only their collections of plant materials, but also the leftover of their ancestor’s collections. This results in a layered nest or midden, containing multiple generations of collected plant material. Because packrats limit their foraging to about 300 feet of their nests, whatever is found is representative of what existed close by. Cemented and preserved by the dry climate and addition of rat urine these middens reveal a history of changing climate and a time when the Grand Canyon was much wetter and colder than today. Packrat middens and dung contain remains that indicate the lower reaches of the Grand Canyon were populated by juniper and ash forests.
Remains of the extinct giant ground sloth and it’s fossilized dung have been found in Rampart Cave in the Grand Canyon. Radiocarbon dating of the dung has yielded ages of 35,000 years for the oldest layers and 11,000 years for the youngest layers. Again, ash and juniper pollen indicated a much wetter and cooler climate.
The significance of the wetter climate data is that much, if not most of the carving of the canyon takes place during large floods of 10-year, 25-year, even 50-100-year return intervals. The bed of the Grand Canyon is covered in gravel and boulder deposits (sometimes as thick as 75 feet) that “armor” the underlying bedrock from erosion by the river most of the time. But the large floods move this bed load and their movement impacts the bedrock like jackhammers; so most of actual carving probably takes place then. At the close of the ice age, when the glaciers were melting, there was a lot more water available to do this carving.
The fact that giant sloths went extinct long before the arrival of humans in the Grand Canyon pose a major problem for the supposed dispersion of animals and humans over planet Earth from the ark’s resting place in the distant Middle East. The time of the so-called dispersion would have had to occur in the last 5,000 years; which allows no time between the arrival of the giant sloths and the arrival of humans. Viewed from the modern geology perspective, the piles of dung that contain plant material from a different climate and that significantly predate the arrival of humans present no real challenges. To quote from page 183:
The span of time represented by radiocarbon ages is consistent with the extended habitation by generations of sloths, the plant material in their dung fits with a more temperate climate during the last ice age, and the subsequent extinction of these creatures is consistent with climate changes that made conditions inhospitable to their way of life.
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Photo by Alan English CPA on Flickr. Creative Commons License.