Survey of Microbial Composition and Mechanisms of Living Stromatolites of the Bahamas and Australia: Developing Criteria to Determine the Biogenicity of Fossil Stromatolites

by Dr. Andrew A. Snelling and Dr. Georgia Purdom on December 18, 2013

Full article at

This paper was originally published in the Proceedings of the Seventh International Conference on Creationism (2013) and is reproduced here with the permission of the Creation Science Fellowship of Pittsburgh.

Understanding Fossil Stromatolites in the Creation-Flood Framework

Since the biogenicity of many Archean stromatolites has now been well established in the relevant literature, it is important to grapple with how and where they fit within the biblical framework of earth history. Added to that is the compelling evidence of stromatolitic reefs that grew in place due to microbial activity as far back as 3430 Ma in the conventional geologic timescale. Wise and Snelling (2005) discussed the options for when Precambrian fossil stromatolites may have formed and under what conditions. There seems to be only three logical possibilities for their origin-they were created by God as fossils, or they were created by God as complete, fully functioning entities, or they developed as a result of natural post-creation, antediluvian growth processes. However, in the case of a given stromatolite all three could be true (a created fossil core, an initially created living stromatolite structure, and subsequent post-creation growth). Furthermore, the creation of a "fully functioning entity" would seem, almost by definition to have involved the creation of a fossil core and allowed for post-creation growth. These thus do not seem to be mutually exclusive possibilities.

Each of these options has its difficulties. Is it reasonable to assume that God would have created a whole Archean stromatolite reef in fossil form? If God created such fossil stromatolites already in fossil form, logically it could be postulated that God created all the fossils as they are. Where then in the geologic record would the fossils have changed from those directly created by God, to those produced by living creatures being buried and fossilized? Yet at some point this must seriously be considered as a possibility in the young-earth creationist model. The wine created by Jesus at the Cana wedding feast (John 2:1-10) simulated wine produced by secondary (natural) processes. Similarly, the bread and fish created by Jesus at the feeding of the 4,000 (Matthew 15:32-38) and the 5,000 (Matthew 14:15-21) also simulated bread and fish generated by secondary processes, and He didn't deceive us about those events because they were recorded for us by eyewitnesses. Thus God does create objects which look like they developed by secondary processes.

The second logical possibility is that the stromatolites were created by God alive as fully functioning entities and then they were buried subsequently by ongoing sedimentary processes. However, given that above the earliest Archean (3.5 Ga) fossil stromatolites in the Western Australian Dresser Formation there is a very thick and extensive Precambrian rock sequence that also contains fossil stromatolites, including stromatolite reef structures spanning from other early Archean stromatolites through to those in the Neoproterozoic (Allwood et al. 2006, 2007; Wise & Snelling 2005), at what point in this strata record did God create the first fully functional living stromatolites? If He only created the earliest fossil stromatolites, those in the lower Archean rock units, then it might be argued that all those fossil stromatolites in the overlying rock units in these thick Precambrian rock sequences would have to have formed by "normal" secondary (natural) processes, which would seem to require an enormous timespan. Then again, there is the likelihood that some (or even many) of those overlying sediments were formed by reworking of previous sediments, and thus the stromatolites could similarly be reworked.

The third logical possibility is that God only created the mat-building microbes, and they then built the first stromatolites that were then buried and fossilized in the Dresser Formation. This possibility is only a small modification of the second possibility just discussed, with a small step back in time for God to create just the mat-building microbes rather than the complete stromatolites in a fully functioning reef. This possibility then requires an enormous timespan for all the subsequent stromatolites and stromatolite reefs fossilized in the thick overlying Precambrian rock sequences to grow and then be buried and fossilized, and/or be reworked.

The choice between these options therefore would seem somewhat arbitrary, since a case could be argued for each. But the difficulty of deciphering at what point in the fossil record is the boundary between the created fossils and then the fossils which formed from creatures that lived and were subsequently buried would seem to rule out the first option. Since the second and third options are closely similar, and God has shown us that He has created fully developed completed entities that appear to have been produced (according to human experience) by secondary processes (e.g. the wine at the Cana marriage feast), then it might be considered reasonable to start with the working hypothesis that God created the first stromatolites as fully functioning living entities, just as He created the first fish, birds, creeping things, beasts of the field, and Adam and Eve. This also makes good sense, in that when God made the soil on the land surface He developed on Day 3 of the Creation Week, He would have also created the microbes in the soil that are part of that fully functioning ecosystem (i.e. as part of the entity they are created in).In the biblical geologic model of earth history proposed by Snelling (2009) it is postulated that the earliest rocks of the geologic record were created and put in place along with the earth's fundamental internal structure during the first two days of the Creation Week. We are not told in the Genesis account what was under those globe-covering waters of those first two days, so we can propose the possibility of the first rocks making the earth's earliest crust, which may have even included marine sediments covering a crystalline basement. Under a global ocean today one would expect marine sediments covering the ocean floor, and in shallower areas these sediments would be carbonates, even containing microbes. So if God created fully functioning entities during the Creation Week as described in the Genesis account, then it is reasonable to postulate that even before Day 3 He could have created the first fully functioning stromatolites with mat-building microbes, quite likely even including stromatolite reefs, with the sediments blanketing the global ocean floor. This is consistent with God creating soil microbes in the soils He made on Day 3.

Then on the Day 3 when God gathered the waters covering the earth into one place and formed the dry land, such actions required catastrophic earth movements to create and uplift a supercontinent. As the supercontinent breached the global ocean, the waters covering the emerging supercontinent were swept aside, and as they drained away they catastrophically eroded that emerging land surface. The sediments carried by those retreating waters in this "Great Regression" would have been deposited at the margins of the supercontinent, with diminishing quantities being spread thinly over the ocean floors around the rest of the globe. Since the emerging land surface would have originally been ocean floor covered in sediments from Days 1 and 2, including carbonates with stromatolites and stromatolite reefs, then these would also have been eroded and reworked. We may thus conjecture the possibility of continued catastrophic deposition from the retreating sediment-laden waters of the Great Regression beyond the continental margins through the remainder of the Creation Week and even into the early part of the pre-Flood era. Such catastrophic deposition would accomplish the rapid accumulation of the thick Archean to mid-Proterozoic sedimentary strata sequences, including entombed stromatolites and microbes, before quieter conditions prevailed offshore, where renewed growth of stromatolites and stromatolite reefs began again as mat-building microbes re-established themselves on and in the shallow offshore carbonate sediments.

This implies that the immense thick sequences of Precambrian sediments enclosing many repeated levels in which stromatolites are found fossilized over wide geographic areas can be fitted into the time period from Day 3 of the Creation Week through the 1650 or so years of the pre-Flood era. This requires mechanisms for both the accumulation of those thick Precambrian sedimentary strata sequences enclosing and fossilizing many stromatolites, microbes and stromatolite reefs reworked from those created prior to the Day 3 Great Regression growing in and on the carbonate sediments of the first global ocean floor, and then for subsequent penecontemporaneous and synchronous growth of stromatolites, microbes and stromatolite reefs in the quieter pre-Flood era offshore conditions, some also being buried and fossilized as pre-Flood sedimentation continued.

This proposed scenario then raises the question as to where in the geologic record the Creation Week-pre-Flood era boundary might be placed. The Scriptures refer to springs and fountains in the pre-Flood world (Genesis 2:6, 10-14; 7:11; Revelation 14:7), and the Archean-Proterozoic geologic record preserves evidence of the activities of those springs and fountains (Snelling 2009). If these springs and fountains were initiated by the catastrophic earth movements when God formed and uplifted the pre-Flood supercontinent on Day 3 of the Creation Week, and these waters were therefore initially very hot from the magmatic activity associated with those earth movements, then this would be reflected in the geologic record accumulated in this dynamic period through the latter part of the Creation Week. That the waters of these fountains and springs were hot and therefore mineral-laden is evidenced by the uniquely Proterozoic, massive banded iron formations (BIFs), volcanic and volcaniclastic strata, and the thick carbonate sedimentary units with their enclosed fossil stromatolites. Since these BIFs are unique to this section of the geologic record (Snelling 2009), it could be argued that they represent a unique period in earth's history. And since their arguably rapid accumulation was accompanied by massive outpourings of volcanics and explosive volcaniclastics, it may be feasible to equate these and the BIFs as having accumulated rapidly during the dynamic period of the Day 3 Great Regression and its aftermath through the remainder of the Creation Week. This would then place the Creation Week-pre-Flood era boundary some place in the geologic record above these BIFs, perhaps even as high as the Paleoproterozoic-Mesoproterozoic boundary (1.6 Ga) (Gradstein et al. 2012).

Wise (2003) proposed that there were extensive fringing stromatolite reefs around the pre-Flood supercontinent. The reef-to-land "lagoon" was probably at least hundreds of kilometers wide, based upon the distribution of the extensive carbonate platforms on which carbonate sedimentary units accumulated during the Precambrian. These stromatolite reefs constituted a stromatolite-hydrothermal biome that only flourished in the pre-Flood era. The hot waters of the fountains and springs not only provided the nutrients for the rapid growth of the microbes responsible for building these fringing stromatolite reefs and the associated stromatolites that grew within the enclosed shallow lagoon waters, but also the voluminous dissolved minerals that were precipitated to accumulate the thick carbonate sedimentary units that entombed and fossilized the stromatolites. The Neoproterozoic Kwagunt Formation stromatolite reef described by Wise and Snelling (2005) would be the fossilized remains of an example of this pre-Flood stromatolite-hydrothermal biome.

The break-up of the pre-Flood supercontinent during the terminal Neoproterozoic at the initiation of the Flood would then have marked the almost complete demise of living stromatolites. The Flood cataclysm began with the breaking up of those fountains of the great deep, the collapse of the margins of the pre-Flood supercontinent, and the rifting of the supercontinent and the ocean basins. The Flood cataclysm then reshaped the earth's surface as it deposited the Phanerozoic geologic record and entombed macrofossils in it. During the catastrophic conditions of the year-long Flood there were not sufficiently long timespans available for microbial activity on transient surfaces to develop into living and growing stromatolites of any significant thickness or geographic extent. This would explain the almost complete lack of fossil stromatolites of any significant thickness or geographic extent in the Paleozoic-Mesozoic strata record of the Flood catastrophe. The microbes which survived through the Flood then re-established their mat-building activities to again grow stromatolites during the waning stages of the Flood through to the present, as seen in the uppermost part of the Phanerozoic strata and fossil records. In the present world living stromatolite remnants are rare and geographically isolated.


Today's rare stromatolites are being built by the metabolism of bacterial microbes in mat communities at the sediment surface-water interface in a few geographically isolated locations. Growth is by sediment grain trapping and binding principally by precipitation of calcium carbonate, resulting in a distinctive cyclical laminar microstructure as the microbial mats repeatedly re-establish themselves at the sediment-water interface. This laminar microstructure and the mat-building microbes are the distinctive features of living stromatolites that are essential criteria in determining whether the relatively abundant Archean-Proterozoic (conventionally 3500-541 Ma) fossil stromatolites are likewise of biogenic origin. A robust set of biogenicity criteria have been established, which include the identification of microbial fossils associated with fossil stromatolites that should be composed of kerogen and have an appropriate carbon isotope signature. Powerful diagnostic techniques that can establish the identity of genuine microfossils have thus confirmed the biogenicity of many genuine fossil stromatolites, and even stromatolitic reefs, as far back in the strata record as the lower Archean (conventionally dated as early as 3496 Ma).

Within the biblical framework of earth history microbes, fully functioning stromatolites and even stromatolite reefs may have been created by God before Day 3 of the Creation Week, as an integral component of the carbonate sediments on the floor of the global ocean. During the Day 3 Great Regression those carbonate sediments, stromatolites and stromatolite reefs could have then been eroded and reworked to be deposited in subsequent sedimentary rock layers, thus accounting for their occurrence in the thick Precambrian sequences. Once re-established in the pre-Flood era, mat-building microbes and stromatolites then flourished in reefs fringing the pre-Flood supercontinent and in the wide lagoons they enclosed, first as sediments were rapidly deposited off the pre-Flood supercontinent's margins after the land emerged, and then continuing on through the pre-Flood era. Their rapid proliferation was facilitated by the mineral-laden hot waters from fountains and springs, which also precipitated the stromatolite-fossilizing extensive thick carbonate strata. The onset of the Flood cataclysm marked the demise of living stromatolites. Unable to establish themselves and grow during the devastation of the Flood, today's rare stromatolites are still being built by those mat-building microbes that survived in a few isolated places with conditions suitable for their growth.