Plain Language Summary

In the papers reviewed here, Dr. Andrew Snelling proposes that the Cambrian aged Tonto Group was deposited over a few days or weeks early in Noah’s flood. He proposes that the sediments were moved at very high flow rates and deposited very rapidly. He further interprets them to have been deformed by faults and folding while the sediments were soft (unlithified), quickly lithified and then eroded rapidly as the Grand Canyon formed. For Young Earth Creation models to be viable, these same rates of deposition, deformation, and often erosion had to occur in sedimentary rocks all around the world.

Here we will describe features that indicate that the Tonto Group sediments were deposited by many different events at much slower rates, with many significant pauses in sedimentation. Such pauses are evidenced by herringbone cross-stratification, mudcracks, trace fossils and stromatolites. When we look at the folding in the Tonto Group, we find that the rocks are clearly fractured and many of these fractures were associated with deformation. We find that the observations at both outcrop and microscopic scales are consistent with low pressure / low temperature deformation over long periods of time. The data indicate a diverse geologic history over deep time. Our geologic understanding has grown over time and many models have been proposed. Even so, we do not find support for a catastrophic flood interpretation either in the Cambrian rocks of the Grand Canyon or in other sedimentary basins around the world.

Introduction

Most lists of the “seven wonders of the natural world” include the Grand Canyon in Arizona. It is spectacular visually but also geologically. This is not just because of the canyon that is carved there but because it exposes so much rock. The modern understanding of the vast majority of geologists is that the rocks were formed over many millions of years. Can they be explained in a much shorter timeframe? Young Earth Creationism (YEC)¹ proposes that the entire universe is approximately 6,000 to 10,000 years old and its proponents have often declared that the rocks along the Grand Canyon and Colorado Plateau can be scientifically interpreted in ways that fit this interpretation. One key component of YEC explanations is the claim that approximately 4350 years ago, the earth experienced a global catastrophic flood, the biblical Noah’s flood, that included many unique events and effects that together comprise an interpretation called “flood geology” (FG).

YEC and PhD geologist Andrew Snelling authored four papers from 2021 to 2023 that claim to demonstrate that a group of Cambrian formations in the Grand Canyon were deposited catastrophically by Noah’s flood. Dr Snelling is the Director of Research for Answers in Genesis, the largest YEC organization online. In his papers, he claims that this key example should be interpreted to have been deposited early in the catastrophic flood and then folded (deformed) while still soft. He further claims that the sediments were then hardened to solid rock (lithified) quickly and then the Grand Canyon carved through this rock. He applied for permission and collected 53 samples from the Cambrian Tonto Group in the Grand Canyon to study the sedimentary rocks and their deformation at microscopic scales.

Snelling’s interpretations sharply contradict modern geologic consensus for these rocks. Despite the length of the reports and the technical details presented, geologists are not likely to be convinced to reinterpret the geologic record in light of this work. Why not? It is not because of their bias against the Bible or some sort of atheistic agenda that pervades modern science. Many scientists, including geologists, are Christians and find that their geologic interpretations do not call into question their faith or the Bible. Geologists will find his arguments unconvincing because the arguments against his interpretation are far stronger than any support he finds in his studies as presented to date.

In this paper, we examine published data available from various studies of the Grand Canyon and other relevant areas, including Dr. Snelling’s reports and the explanations that he provides. Dr. Snelling shows good knowledge of existing publications in his documents. The technical descriptions of the thin sections are well done and have accurate observations. (Thin sections are samples of the rock mounted on glass slides and ground to thicknesses of 30 µm for examination on special petrographic microscopes.) Many non-geologists are likely to be impressed with all of the technical detail and language utilized. It may seem quite impressive to those without the background or skills to critique it, and they may assume his conclusions are reasonable.

Contradictions with the geologic understanding developed for the formations of the Tonto Group can be summarized by the answers to the following four questions:

1. How long did it take for the unit to be deposited? Thousands to millions of years vs. a few days.
2. What depositional processes were dominantly involved? Fluvial and tidal processes vs. catastrophic flood processes.
3. How were the rocks deformed? Slow tectonic processes over millions of years vs. rapid soft sediment deformation over days.
4. What is the general age model for when the rock was formed? ~500 million years ago vs. less than 10,000 years ago.

The differences between these two models are major and as a result, both cannot be true. One or the other is false. In this case, if any of these four questions can be demonstrated not to be reconcilable with FG, then YEC should not consider these Cambrian units as “flood deposits” and it makes the entire YEC proposal questionable. In this current report, we will address primarily the first three questions. We believe that the general age model developed using radiometric dating is sound, but we will leave that question for future reports.

Figure 1² shows two current contrasting YEC interpretations for the timing of Noah’s flood in the geologic record from separate leading YEC organizations. Both groups recognize that, regardless of their differences with the accepted timescale, the accepted geologic column is a valid summary of many, many observations around the world. The relative order of sediment deposition is recognizable. The key difference in the two interpretations is in the top of the flood interval. Snelling interprets the top of the flood interval as the top of the Mesozoic section and that gives him very limited time for the deposition of the Tonto Group. Dr Tim Clarey of the Institute for Creation Research (ICR) places the top of the flood deposits at the top of the Pliocene and therefore, leaves even less time available for each system of rocks to be deposited, including the Tonto Group as illustrated on the figure. In many places around the world, the differences between these views involves literally miles of sediment thickness.

Table 1 is a summary of our findings in the form of a “stoplight chart”, such as is commonly used in the oil industry to convey risks and uncertainties associated with particular plays or prospects. Green signals show that the data support the proposed model, while red signals reflect potentially fatal flaws that would need to be addressed in order for the model to be considered viable. The column for Old Age Models reflects not one single model, but whether or not concerns have been identified that would make depositional processes acting over deep time doubtful. The column for FG also does not reflect a particular FG model, but whether concerns are recognized that would invalidate the general explanation for the Cambrian rocks being deposited by a global catastrophic flood. The colors are subjective appraisals of the evidence but provide a quick visual assessment of what we have found.

Notice that the stoplight column for Old Earth is all green. That means that we interpret that all of the evidence can comfortably be interpreted within an Old Earth framework. This includes the data provided by the Snelling reports and all other published materials that we have reviewed. Geologists have had different depositional models and structural understandings, but all involve far longer timeframes than are available in the YEC timelines. Although ideas will continue to develop, there is no reason to believe that future models will alter in ways that call into question the general concept of deep time.

Notice that the stoplight column for the Young Earth models includes largely reds and yellows. This means that we find many observations that are difficult or impossible to reconcile with the YEC models or with FG in general. Dr. Snelling and other YEC authors must provide better explanations for many of the observations that we note in this table. We consider their explanations to be inadequate or invalid in most cases. We plan to provide more detailed information in future papers, but will summarize our findings here.

Part Two will concentrate on how long it took for the Cambrian sediments to be deposited and what processes are evidenced. It is worth noting that for FG models to be considered viable, every hill is a hill to die on. Given their interpretation of the Genesis text, all of the flood deposits had to take place over 371 days. Any rocks that took longer than this to form must be excluded from their flood deposits. This applies not just to individual beds, but to each set of beds and formation.

We will look at several examples that don’t fit the flood models. The published interpretations tell us approximately how many days YEC models propose were available to deposit rocks in each of the geologic periods, regardless of how long these periods actually were. The duration of each of these periods, including the Cambrian period provide reality checks that we can use to see if the YEC models are viable. (See Figure 1).

We can also look at the rocks to see if the depositional clues in them are consistent with the proposal of catastrophic flood deposition. Naturally the range of processes recognized in the Tonto Group is more limited than what we would find in the entire rock record, but if these were, as Snelling asserts, deposited by a catastrophic flood, we can be confident that some processes will not be recognized.

Thus in this part, we will point out several clear indications that sedimentation was not rapid or continuous. It clearly shows that the Tonto group had significant pauses in sedimentation. Parts just were not deposited by water moving at the rates that Snelling claims.

Part Three will look at what happened to the sediments after they were deposited. This is particularly relevant to Snelling’s reports. He sampled 53 rocks from the Tonto Group, but the rocks were not selected to systematically examine the depositional facies present. They were selected to help him demonstrate that the folding in the Tonto developed before the sediments were lithified, that is turned into hard competent rocks.

This again is a hill to die on for flood geology. If any of the rocks had been lithified first and then deformed afterward over the Young Earth timeframes, they would not have folded. They would have behaved brittlely, exclusively through faulting and shattering. Snelling sampled beds that were faulted and fractured, but also folded. He seeks to demonstrate that sediments were soft at the time of their deformation. In Part Three, we will look at evidence, including some that comes directly from Snelling’s slides, that shows that what we find is just what we should expect to find if hard rocks were deformed slowly of deep time.

We will look at the diagenesis, those changes in the sediments after deposition. Loose sands were hardened over the broad areas of today’s Colorado Plateau dominantly by quartz cementation. This takes place slowly over thousands of years or more, and in this case, it occurred prior to carving of the Grand Canyon and the folding. YEC time models predict that this would have happened over 450 years. This, like other findings is problematic for YEC models. While our findings do not support the Young Earth interpretation of the rock record, they do not speak to other interpretations of Genesis or the Christian faith. It is our hope that YEC will recognize that the geology does not support Snelling’s conclusions.