The Proceedings of the Eighth International Conference on Creationism (2018)

various Cenozoic ages, consistent with 40 Ar/ 39 Ar ages of supergene alunite and jarosite associated with the weathering of other similar ore deposits within the Iberian Pyrite Belt. These results are exactly as anticipated if weathering started after the retreating Flood waters had exhumed much of the current landscape. It is to be expected there would be a range of ages for the formation of supergene minerals, as some would start forming where weathering commenced as the Flood ended, and then further supergene minerals would form later in the early post- Flood decades in areas that experienced residual catastrophism and erosion which delayed the onset of weathering. Thus, the retreating Flood waters would have rapidly eroded off the overburden covering many primary ore deposits, and then as the Flood ended the supergene weathering began. Subsequently, it would have required the extended time in the decades after the Flood for the chemical reactions to produce these supergene minerals from their primary precursors. The relative ages of formation of all these supergene minerals thus date the beginning of weathering reaching the level where the precursor primary ore minerals occur, but erosion and weathering would have started well before that date. So, in the context of the Flood, as the waters retreated erosion occurred and then weathering could have begun while Noah was still on the Ark. However, there would have been insufficient time in the closing weeks of the Flood for chemical weathering to have generated large enough quantities of supergene minerals for dating. Thus, if the Flood/post-Flood boundary is placed at the K-Pg boundary in the geologic record (a relative date of 66 Ma) (Austin et al. 1994; Whitmore and Garner 2008), then it is not unexpected that only a few of these relative ages for supergene mineral formation would slightly pre-date that boundary (the >66 Ma dates in Fig. 1). Much caution obviously needs to be exercised in interpreting all these data. Nevertheless, this is a line of investigation that could still potentially yield some demarcation of where the Flood/post- Flood boundary should be placed in the geologic record. Thus, these relative ages of formation of supergene minerals from end- Flood and post-Flood weathering appear to be consistent with a Flood/post-flood boundary low in the Cenozoic, likely as low as the K-Pg boundary many Flood geologists prefer based on many other criteria (Austin et al 1994; Snelling 2009; Whitmore and Garner 2008; Whitmore and Wise 2008). CONCLUSIONS The radioisotope dating methods cannot produce absolute ages because of the demonstrated violations of the three assumptions foundational to them. Nevertheless, because many sources of error are systematic, these methods can still produce relative ages, that may then be useful in determining where rocks and minerals fit in the geologic record. It has also been shown that the so-called geological column is likely a reasonable representation of the geologic record of earth history, especially as the global extent of some fossil-bearing sedimentary layers and the megasequences that contain them are powerful evidence of the global Flood cataclysm as described in the Genesis account. Those who dispute the integrity and usefulness of this geologic record use minor exceptions to disparage this “big picture” Flood evidence, and fail to propose an alternative coherent Flood model consistent with the physical rock record. When the Flood waters retreated after likely peaking on Day 150, major erosion occurred. By Day 314 the Genesis account says the face of the ground had dried, but Noah waited another 57 days before God instructed him and his cargo to leave the Ark. The ground surface may have been dry, but extra time was needed to allow the water table to drop, soil to form and plants to grow. Thus, the weathering front started to progress downwards, a process that would have been a major shaper of the land surface and topography in the early post-Flood era, in which it required decades for the chemical weathering reactions to produce the supergene minerals. Primary ore deposits were formed at depth before and during the Flood, but the erosion by the retreating Flood waters stripped away enough of the cover rocks for weathering of their tops to commence after the Flood ended and for supergene minerals to start forming post-Flood. Subsequent residual post-Flood catastrophism may have involved mountains still rising and ore deposits still forming, such as the porphyry copper deposits associated with granite intrusions as the Andes continued to rise. The erosion to expose those later-formed ore deposits and the subsequent weathering to produce supergene minerals from them may thus have occurred well into the early post-Flood era. The supergene iron oxides, and potassium-bearing sulfates and manganese oxides, produced by weathering of ore deposits can be radioisotope dated to yield the relative ages of their formation. The relative ages obtained span the whole Cenozoic, indicative of progressive weathering and initiation of supergene mineral formation through the Cenozoic. Thus, it is proposed that the relative dates for the first formation of supergene minerals can be used as a helpful criterion for determining the placement of the Flood/post-Flood boundary in the geologic record. The relative ages of supergene minerals thus favor a placement at the K-Pg boundary with a relative age of 66 Ma, the Flood/ post-Flood boundary favored by many Flood geologists. The few slightly earlier relative ages likely resulted from weathering that commenced before Noah stepped off theArk to end the Flood event, while the spread of relative ages through the Cenozoic represents the progressive formation of supergene minerals as primary ore deposits emplaced during, and some maybe after, the Flood were subsequently exposed to weathering by residual catastrophism. Continuing investigation of this criterion for placement of the Flood/post-Flood boundary seems warranted. ACKNOWLEDGMENT Two anonymous reviewers are thanked for their critical comments and suggestions which resulted in this paper being greatly improved. REFERENCES Alpers, C.N., and G.H. Brimhall. 1988. Middle Miocene climatic change in the Atacama Desert, northern Chile: Evidence from supergene mineralization at La Escondida. Geological Society of America Bulletin 100:1640-1656. Anderson, L.A., Jr. 2014. Waves of opinion: The chronology of the Flood in literature past and present. In Grappling with the chronology of the Genesis Flood: Navigating the flow of time in biblical narrative , eds. Snelling ◀ Flood/post-Flood boundary ▶ 2018 ICC 560