March 5, 2006 | David F. Coppedge

Little Colorado Grand Falls Much Younger Than Thought

The Little Colorado River makes a dramatic drop over a lava cliff in Arizona after going around a lava flow.  Previous estimates dated the lava at the falls at 150,000 years old (150ka).  Now, a team of geologists publishing in GSA Bulletin1 used multiple methods that dated it at no more than 19,600 years old (19.6ka) – one eighth the earlier age estimate.  Here were some of their reasons for the revision:

The ca. 150 ka age of the Grand Falls flow provided by whole-rock K-Ar analysis in the 1970s is inconsistent with the preservation of centimeter-scale flow-top features on the surface of the flow and the near absence of physical and chemical weathering on the flow downstream of the falls.  The buried Little Colorado River channel and the present-day channel are at nearly the same elevation, indicating that very little, if any, regional downcutting has occurred since emplacement of the flow. (Emphasis added in all quotes.)

Many people might expect radiometric dating of lava to be straightforward, but the authors began by casting doubt on the most widely-used methods: “Dating Quaternary mafic volcanic materials has proven to be challenging in many cases,” they said.  “K-Ar and 40Ar/39Ar are the most common dating methods, but results may be difficult to interpret because so little potassium is present in these rocks and because the rocks may also contain excess Ar from mantle or crustal sources.”
    They employed four independent methods that more or less converged on the approx. 20,000 year figure.  That would seem to settle the matter, but in their discussion, they said: “The question remains of how to decide what relative weight to apportion to each dating technique in trying to accurately define when the lava dam formed.  Each technique includes its own set of assumptions and uncertainties.”
    Perhaps eyeball dating should be given more weight.  The authors took notice of how little erosion had occurred in this area.  They estimated downcutting rates, but then said of four lava flows in the area, “These emplacement units lack evidence of physical erosion or chemical weathering, both within the stack of flows and at the basal contact of flows with underlying columnar basalt.  The flows may simply represent overlapping lobes of a single lava flow.”  Speaking of dust on top of the flow, they said, “All features not covered by eolian [wind-blown] sediment appear to represent original or nearly original surfaces of lava that have been little weathered or eroded, if at all, since their formation.”
    Considering that whole cities have been embedded in dust in recorded history, perhaps even 20,000 years is too much.  They ended by discussing possible reasons why the earlier estimate was so much older, and warned of misinterpretation because excess argon may be a bigger problem than previously realized.  Even so, “However common excess Ar may be in lava of the volcanic field, caution is advised in all time-related generalizations about the growth of the field, including interpretation of the 100 m/m.y. rate of regional downcutting calculated from whole-rock K-Ar ages for samples from the two older lava dams along the Little Colorado River.”  Does anybody really know how old this lava flow is?


1Champion et al., “Multiple constraints on the age of a Pleistocene lava dam across the Little Colorado River at Grand Falls, Arizona,” Geological Society of America Bulletin, doi: 10.1130/B25814.1, : Vol. 118, No. 3, pp. 421�429.

Unless you subscribe to the Creation Research Society, Institute for Creation Research or the Creation Technical Journal, you may have been completely unaware of the quality of young-earth creation research that has been independently published for decades.  Such research is so completely barred from the usual journals, creation geologists, astronomers and biologists have continually published their own work, with a few exceptions making it into the mainstream.  Many of their papers are just as rigorous and scholarly as those in the secular journals.  They would be indistinguishable except for the rags they’re printed in.
    Recently, Carl Froede and Emmett Williams investigated the same Grand Falls area.  This gives you an opportunity to compare one example of OEE (old-earth evolutionist) and one example of YEC (young-earth creationist) interpretations of the same spot.  Publishing in Creation Research Society Quarterly, Froede and Williams found much more evidence for youthfulness of the area than admitted in the GSA paper.  They found delicate structures, very little erosion of the basalt, and lack of evidence of substantial weathering.  Their common-sense approach based on clear, observable features was supported by photographs and measurements.  They challenged,

The flow appears to be of a recent origin by nature of its excellent preservation.  This is empirical evidence.  Why do uniformitarians force the time issue by adopting inappropriate age-dates?.  Unfortunately, they are forced to interpret and skew data in an attempt to bolster an archaic, unrealistic, and nonscientific model of Earth history.

Note that the Grand Falls lava flow does not appear any older than lava flows known to have been emplaced within historic times.
    One other thing.  How many earth science students were told confidently by evolutionary geologists in the 1970s that this lava flow was 150,000 years old?  Did any of the students question the Biblical chronology based on what is now known to be false?  Should any of today’s students trust the new estimate of 20,000 years, when the authors admit that “caution must be exercised in interpreting” dating methods?  When fallible experts cannot agree, when they keep changing their numbers, when they are forced into their positions by a priori assumptions about the age of the earth, and come up with conclusions that go against common sense, shouldn’t new ideas be given a fair hearing?

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