Journal of Creation 36(3):9–10, December 2022
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‘Ice-rafted’ dropstones from warm-climate cap carbonates?
Ice-rafted dropstones are thought to be one indication of an ancient ice age. However, they are equivocal as an indicator of glaciation, since several other processes can duplicate dropstone rhythmites.1 Ice-rafted dropstones are not expected to occur in warm-climate sediments. However, dropstones have recently been found in a cap carbonate,2 which is accepted as evidence of a warm climate that melted several global Neoproterozoic ‘ice ages’. This has presented a conundrum for uniformitarian scientists:
“Dropstones of ice-rafted origin are typically cited as key cold-climate evidence in Cryogenian strata [from the Neoproterozoic] and, according to conventional wisdom, should not occur in postglacial warmwater carbonates.”3
What are cap carbonates?
Cap carbonates are found above ‘glacial deposits’ of most of several Neoproterozoic ‘ice ages’. These ‘ice ages’ are mostly considered global ice ages because the evidence for them is found in marine strata at low paleolatitudes based on paleomagnetism.1 Cap carbonates especially cover the Marinoan ‘ice age’ all over the world and sometimes the Sturtian ‘ice age’ of the Cryogenian.4 They can be up to several tens of metres thick.5 Cap carbonates cover 45,000 km2 in the Neoproterozoic glaciation from the Adelaide Rift.
The cap carbonate above the ‘glacial’ Chuos Formation
The Chuos Formation, in Namibia, is considered to be deposits from an ancient Neoproterozoic ice age. Above it is a cap carbonate that “is interpreted to record the abrupt change to a significantly warmer greenhouse climate.”3 The Chuos Formation is marine, based on the presence of foraminifera fossils. The researchers postulate that the occurrence of dropstones in a warm-climate rock was caused by ‘vestigial glaciation’, probably meaning glaciation from some distant land in which icebergs floated over the warm water. The ‘dropstones’ do appear to have been dropped from above:
“Most lonestones [isolated dropstones] exhibit both impact structures beneath them and draping laminations (undisturbed dololaminae) above them.”6
The Chuos Formation has bounced back and forth as originating either from glacial ice or non-glacial mass flow. Eyles and Januszczak concluded that the Chuos Formation is entirely a mass flow deposit.7 It is interbedded with other mass flow sediments, such as conglomerates and sandstone turbidites. Le Heron et al. acknowledge the presence of mass flow sediments, but they also believe that the formation is glacial,2 probably because of the presence of dropstones that they think can only be carried by ice (see below).
Most cap carbonates are cap dolostones
The cap carbonate is supposed to have formed in a warm climate. This is supported by the fact that most of the cap carbonates are dolostone. Primary dolostone, and even replacement dolostone, requires water temperatures greater than 100°C.8,9 Previous to this, no dropstones had been found in cap dolostone:
“This finding [dropstone dolostone] is significant, because ‘no convincing dropstone has been confirmed from cap dolostone units anywhere in the world’ (Shields, 2005, p. 301).”
The comparatively hot temperatures required for the deposition of cap dolostones are a good indication that the supposed glacial deposits are not really glacial. The evidence for glaciation, including supposed glacial indicators, can be explained by gigantic submarine mass flow during the Flood.1 Mass flow can mimic all the glacial indicators for ancient glaciations. In support of this, part of the cap dolostone itself shows evidence of mass flow.2
Belief in evolution eliminates all dropstone mechanisms except for ice rafting
Probably the primary reason that Le Heron et al. still believe the Chuos Formation is glacial and that the cap dolostone represents vestigial glaciation is that they cannot think of a mechanism, other than from ice, for dropstones in the Neoproterozoic. This belief is based on evolution, in which there would be no seaweed, such as kelp, to explain dropstones in the Neoproterozoic.
Dropstones from the Genesis Flood
When the Creation and the Flood are considered, and realizing that the Neoproterozoic is very likely early Flood rocks,10 it opens the door for other explanations. Eyles and Januszczak even considered such floating stones in the cap carbonate as evidence of mass flow.7 Other aspects of pre-Pleistocene ice ages—rocks of various sizes in a fine-grained matrix, striated pavements, striated and/or faceted rocks, and other supposed glacial indicators—can be explained by gigantic submarine mass flow during the Genesis Flood.1 But, in the Flood, trees and kelp would have existed from the beginning and, therefore, the stones could have been dropped from floating tree roots (figure 1) or kelp torn up during the Flood.
References and notes
- Oard, M.J., Ancient Ice Ages or Gigantic Submarine Landslides? Creation Research Society Books, Chino Valley, AZ, 1997. Return to text.
- Le Heron, D.P., Busfield, M.E., and Kettler, C., Ice-rafted dropstones in ‘postglacial’ Cryogenian cap carbonates, Geology 49(3):263–267, 2021. Return to text.
- Le Heron et al., ref. 2, p. 263. Return to text.
- Shields, G.A., Neoproterozoic cap carbonates: a critical appraisal of existing models and the plumeworld hypothesis, Terra Nova 17:299–310, 2005. Return to text.
- Rose, C.V. and Maloof, A.C., Testing models for post-glacial ‘cap dolostone’ deposition: Nuccaleena Formation, South Australia, Earth and Planetary Science Letters 296:165–180, 2010. Return to text.
- Le Heron et al., ref. 2, p. 264. Return to text.
- Eyles, N. and Januszczak, N., Syntectonic subaqueous mass flows of the Neoproterozoic Otavi Group, Namibia; where is the evidence of global glaciation, Basin Research 19:179–198, 2007. Return to text.
- Oard, M.J., A more likely origin of massive dolomite deposits, J. Creation 36(1):4–6, 2022. Return to text.
- Oard, M.J., The ‘dolomite problem’ solved by the Flood, CRSQ (in press). Return to text.
- Oard, M.J. and Reed, J.K., How Noah’s Flood Shaped Our Earth, Creation Book Publishers, Powder Springs, GA, 2017. Return to text.
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