Roraima

Unsupported Young-Earth Creationist (YEC) Claims of Pollen and Spores in the Precambrian Roraima Supergroup of Guyana

Kevin R. Henke, Ph.D.

December 11, 2015

Introduction

For the most part, young-Earth creationists (YECs) are fundamentalist/evangelical Christians. They believe that the Earth was literally created in six 24-hour days according to Genesis 1 in the Bible and that most or all sedimentary rocks formed during Noah’s Flood (Flood geology) as described in Genesis 6-9. Their religious beliefs lead YECs to reject biological evolution and a 4.55 billion year old Earth. Based on the genealogies, lifespans of the Patriarchs and other claims in the Bible, YECs generally believe that the Earth and the rest of the Universe are only 6,000 to 10,000 years old and that Noah’s Flood occurred roughly 4,500 years ago.

Over the years, a number of YECs have sought scientific evidence to support Flood geology and a young Earth and to refute biological evolution, the Big Bang, radiometric dating or anything else that challenges the validity of their biblical interpretations. One of their arguments against plant evolution and for Flood geology involves claims that “out-of-place” fossil angiosperm, gymnosperm and other plant pollen have been found in the rocks of the Grand Canyon, including the Precambrian Hakatai Shale, the Permian Supai, the Cambrian Bright Angel Shale, and shaly layers in the Mississippian (Lower Carboniferous) Redwall Formation (Howe 2003; Howe et al., 1988; Anonymous, 1981, p. 3; Howe, 1986, p. 100; Lammerts et al. 1987; Kofahl and Segraves 1975). According to our current knowledge of plant evolution, many of these plants hadn't yet evolved during the Precambrian and Paleozoic.

The late Clifford Burdick was a leading YEC proponent of “out of place” Precambrian and Paleozoic pollen in the rocks of the Grand Canyon. Henke (2005) provides a response to these claims. Since 2005, the claims of Clifford Burdick and his associates for the presence of “out of place” pollen in the Grand Canyon rocks have been largely forgotten by the leading advocates of young-Earth creationism at Answers in Genesis, Creation Ministries International and the Institute for Creation Research. Instead, YEC Emil Silvestru (2012) has argued for the presence of “out of place” pollen and spores in the Paleoproterozoic (Precambrian) Roraima “Formation” (now a Supergroup), which is located in Guyana and surrounding areas of Venezuela and Brazil. YECs want to use these claims to destroy support for plant evolution and the geologic time scale.

Case 1: Allen (1967) Ends the Bailey (1964) Controversy over Microfossils in the Roraima “Formation”

YEC Silvestru (2012) cites Bailey (1964) and Stainforth (1966) as early reports of microfossils in the Roraima Supergroup of British Guiana (now Guyana). Bailey (1964) described possible organic microfossils as coming from Roraima “Formation” stream pebbles and boulders in the Kako River, which is located in western Guyana (Figure 1). Rather than identifying the possible microfossils as pollen or spores, Bailey (1964) thought that the “organic” materials resembled foraminifera or radiolaria.

Allen (1967) is an important response to Bailey (1964) that Silvestru (2012) either overlooked or failed to mention. Allen (1967) disagreed with Bailey (1964) and argues that the “microfossils” are actually volcanic ash particles. Allen (1967, p. 1262) states:

“The present communication is not intended to comment on any aspect of the Roraima Formation but to correct the impression that the microscopic objects figured by Bailey [1964] are of organic origin. Bailey's photomicrographs were taken by me, and I have examined a number of thin sections of the 'type-material', including specimen H 265. In my view, all the features observed under the microscope are consistent with a pyroclastic origin for these small bodies, which display the characteristic morphology of globular areas of vesiculated volcanic glass in varying stages of disruption.”

“Disruption” probably refers to alteration of the particles. In the presence of air and water, volcanic glass typically alters to clays, iron oxides and other materials over time. The photographs of “microfossils” in Bailey (1964) and Allen (1967) do indeed strongly resemble microscopic volcanic glass particles.

Bailey (1964) even admits that “sponge spicule” fossils found in the Roraima “Formation” may actually be volcanic glass shards. So, Allen (1967) was not the only individual to think that the “microfossils” of the Roraima Supergroup were actually volcanic glass particles. Considering Dr. Allen’s expertise and familiarity with the samples, there is little doubt that Allen (1967) is correct and that Bailey (1964) misinterpreted particles of volcanic glass as fossils. After Allen (1967), the claims in Bailey (1964) were largely forgotten.

Case 2: Stainforth (1966) Claims of Actual Pollen and Spores in Roraima “Formation”

Unlike the samples discussed by Bailey (1964), several palynologists participated in the research discussed in Stainforth (1966) and apparently genuine pollen and spores were recovered from samples of the Roraima Supergroup. Although the opinions of the palynologists mentioned by Stainforth (1966) varied over the age of the pollen and spores, none of them advocated an age older than the Mesozoic. Even though both articles were published in Nature, Allen (1967) does not cite Stainforth (1966) and may have been unaware of its existence.

Figure 1. Locations of claimed microfossils found in the Paleoproterozoic (Precambrian) Roraima Supergroup in western Guyana (Stainforth 1966; Silvestru 2012). Allen (1967) argued that “organic microfossils” reported by Bailey (1964) from Roraima “Formation” (now Supergroup) gravels at the Kako River, British Guiana (now Guyana), were actually microscopic particles of volcanic glass. Stainforth (1966) claims that Tertiary and perhaps Mesozoic pollen and spores were found in hornfels (contact metamorphic rocks) from the Roraima “Formation” from near Paruima and Cerro Venamo, Guyana.

Geology and Locations of Roraima Supergroup Pollen- and Spore-bearing Samples

The general geology of the Roraima Supergroup is shown in Figure 2 and is based on Figure 4 in Schneider-Santos et al. (2003, p. 336). The host rocks of the pollen and spores discussed in Stainforth (1966) are hornfels, which are low-pressure contact metamorphic rocks that form from subsurface sedimentary rocks being heated or “baked” by magmas. Unlike igneous rocks, hornfels and other metamorphic rocks do not form from melts. Although the sedimentary rocks in immediate contact with the magmas would have melted, hornfels form under cooler conditions farther away from the pluton. Based on descriptions and discussions in Stainforth (1966) and Schneider-Santos et al. (2003), Silvestru (2012, p. 55) concluded that the pollen- and spore-bearing hornfels came from the Cuquenan Formation in the Roraima Supergroup (Figure 2). The Cotingo Sill (Figure 2) may have been responsible for metamorphosing the Precambrian sedimentary rocks into hornfels.

The pollen- and spore-bearing hornfels discussed in Stainforth (1966) were collected near Cerro Venamo, Guyana on the border with Venezuela, and Paruima, Guyana (Figure 1). U.C.K. Dunsterville collected samples near Cerro Venamo in late 1963 (Stainforth 1966). The samples were processed by palynologists G. Fournier, L. Nijssen, and J.A. Sulck and “well-preserved” pollen and spores were recovered and identified. In April 1964, a team of geologists went to the Cerro Venamo region and collected more samples (Stainforth 1966). Samples believed to have come from the Roraima “Formation” were also collected near Paruima, Guyana, on the Kamarang River, about 40 kilometers from the Cerro Venamo sites. The Paruima rocks contained the same microfossils as those found in the Cerro Venamo hornfels (Stainforth 1966).

The Paruima and Cerro Venamo hornfels contained the metamorphic minerals cordierite and andalusite (Stainforth 1966). A photograph of the Paruima hornfels in Figure 2 of Stainforth (1966) shows the original sedimentary quartz bedding and cordierite, as well as metamorphic grains of biotite and muscovite (micas). Stainforth (1966) quotes H.H. Hess as indicating that X-ray diffraction analyses did not detect clay minerals and chlorite in the hornfels. According to the text and the graph of Figure 1 of Silvestru (2012, p. 55), the absence of chlorite and the presence of cordierite, andalusite, and possibly biotite in the hornfels indicate hornblende facies metamorphism and metamorphic temperatures of about 500-700^oC. Depending on the amount of water and quartz that is presence, muscovite also may be stable in the hornblende facies (Winter 2001, pp. 574-577; Best 2003, pp. 430-436). So, contrary to Silvestru (2012, p. 57), these hornfels are typical.

Figure 2. General geology of the Roraima Supergroup of Guyana and surrounding areas of Venezuela and Brazil, modified from Figure 4 in Schneider-Santos et al. (2003, p. 336). Not to scale. Some researchers (e.g., Sauro 2014) include the Mataui Formation in the Roraima Supergroup. The pollen and spores mentioned in Stainforth (1966) may be from the Cuquenan Formation (bolded). The formations are commonly intruded by diabase (dolerite) plutons, which are shown in light brown.

Based on the photograph in Figure 2 of Stainforth (1966), Silvestru (2012, p. 57) claims that the “roundness” of the cordierite grains could indicate that they are detrital. Detrital grains are fragments of rocks and minerals in sediments that have been transported, usually by liquid water. Although not much can be determined from a single photograph, the cordierite grains appear euhedral to subhedral and a detrital origin for the grains is unlikely. Well-crystallized and unaltered cordierite is pseudohexagonal and prismatic (Klein and Hurlbut 1999, p. 473), which would explain the “roundness” of the mineral cross-sections in the thin section photograph in Figure 2 of Stainforth (1966). Hexagonal-shaped cordierites are even visible in the Stainforth (1966) photograph. Considering the susceptibility of cordierite to alteration (Klein and Hurlbut 1999, p. 473), if the cordierites were detrital as Silvestru (2012, p. 57) suggests, then it is likely that they would have been noticeably weathered and clay minerals (especially pinite) should have been present within the grains. Although the mineralogical descriptions in Stainforth (1966) are far from adequate, why were clay minerals and chlorite not detected in the X-ray diffraction analyses if the cordierites are detrital?

The Age of the Sediment Precursors of the Roraima Supergroup Hornfels and YEC Options

Beyer et al. (2015) extensively studied samples from the Roraima Supergroup in locations to the southeast of Paruima and Cerro Venamo, Guyana near Mt. Roraima, Venezuela (Figure 1). Descriptions of the (meta)sedimentary rocks in the Roraima Supergroup indicate that they have a prolonged history and sometimes were deposited under dry conditions. For example, Beyer et al. (2015, Table 1, p. 232) mentions weathering rims on conglomerate grains in the Supergroup. Weathering rims indicate prolonged exposure to air and water. Eolian (wind-blown) grains and playa lake deposits also occur in the Supergroup and they result from subaerial exposure and water evaporating under dry conditions (Beyer et al. 2015, Table 1, p. 232). This information creates problems for YECs. YECs would have four possible explanations for the origin of the Supergroup sediments under their worldview:

1. Deny the evidence and claim that the rocks did not experience prolonged weathering and windy and dry conditions. Instead, the rocks quickly formed early in Noah’s Flood.

2. The evidence of dry conditions and weathering is true. The 3,000-meter thick sequence of (meta)sedimentary and igneous rocks somehow formed during the pre-Flood period, which began with the end of the Creation Week and lasted until the beginning of Noah’s Flood. YECs commonly believe that the pre-Flood period lasted for approximately 1,656 years (Snelling 2009, pp. 265, 613; Wise 2002, p. 265; Austin 1994, p. 66).

3. The evidence of dry conditions and weathering is true. The 3,000-meter thick sequence of (meta)sedimentary and igneous rocks somehow formed very recently in the 4,500 years or so after the Flood.

4. The rocks formed through a mixture of miracles and catastrophic natural processes during Days 3-6 of the Creation Week.

However, each of these scenarios are unproven and unnecessary. How could rocks form under dry conditions during a Flood? How could sediments with a thickness of 3,000 meters or more accumulate in only 1,656 or even 4,500 years? Why are these pollen- and spore-bearing rocks devoid of larger plant or other fossils? Where are the leaves, twigs and root casts? Also, where is the evidence that even one miracle was responsible for the origin of the Roraima Supergroup sediments? Why rely on stories from Genesis when the rocks of the Roraima Supergroup can be readily explained by the laws of chemistry and physics acting over time without invoking any groundless miracles?

Identification and Possible Origins of the Pollen and Spores in Stainforth (1966)

According to Stainforth (1966), G. Fournier concluded that the Roraima pollen was unlike modern pollen from the area. As discussed in Stainforth (1966), researchers argued that the pollen was Tertiary, and perhaps as old as the Mesozoic in some cases. Stainforth (1966) proposed two explanations for the pollen and spores, neither of which involved young-Earth creationism.

The first explanation states that the radiometric dates are correct and that the Roraima “Formation” is Precambrian. Although the possible survival of microfossils during metamorphism was not well understood in 1966, geologists back then generally expected organic microfossils to be converted to graphite (graphitization) and destroyed during metamorphism. The presence of microfossils in the hornfels would be best explained by rainwater carrying pollen and spores into the subsurface during the Tertiary and possibly as early as the Mesozoic. The resulting groundwater would have deposited the pollen and spores in largely unnoticed microscopic openings in the subsurface hornfels. In support of this hypothesis, Stainforth (1966) described what happened to Mesozoic and Cenozoic pollen when some of the samples were treated:

“T. van der Hammen (Leiden) recognizes a mixture of Mesozoic and Cenozoic elements, but suspects that they represent foreign material concentrated along cleavage planes as, after cleaning fragments ultrasonically, he found the matrix practically barren.”

The second explanation argues that the hornfels were too impermeable for pollen and spore contamination. The microfossils were deposited in the original sediments and survived metamorphism. The radiometric dates are incorrect and the rocks are actually Tertiary to Mesozoic. In the 1960’s, proponents of the second explanation were skeptical of the radiometric dates because of the overlap in the dates between the dikes in the thick Roraima “Formation” and rocks underlying the “formation” (Stainforth 1966). The deposition of the thick Roraima “Formation” would have taken considerable time before the dikes were intruded. Today, the stratigraphy and geochronology of the Roraima Supergroup is far better understood (Schenider-Santos et al. 2003; Beyer et al. 2015). Beyer et al. (2015, pp. 246-247) suggest that the length of time between the last deposit of the Roraima Supergroup sediments and the onset of the intrusion of the mafic plutons is about 80 million years.

Proponents of the second hypothesis also argued that if the pollen and spores infiltrated into the subsurface over millions of years, why do the samples not contain mixtures of pollen grains of different ages? However, the rocks probably do contain a mixture of Tertiary and Mesozoic pollen. Considering that the different experts interviewed by Stainforth (1966) dated the pollen and spores anywhere from Mesozoic to Pliocene and that the Roraima Supergroup was only uplifted and exposed to near-surface groundwater in the last 110 million years (late Early Cretaceous) or so (Mecchia et al. 2014, p. 118), a mixture of pollen and spore contaminants of different Mesozoic to Tertiary ages would be expected.

Most Likely Explanation for the Pollen and Spore Claims in Stainforth (1966)

Recent radiometric dates on the plutons and other rocks associated with the Roraima Supergroup indicate that the sediments of the Supergroup were indeed deposited about 1.8 to 1.9 billion years ago (Schenider-Santos et al. 2003). Stainforth (1966) contains no photographs of the pollen and spores found at Paruima and Cerro Venamo. So, we are only left with the inadequate descriptions given by Stainforth (1966). Unlike the situation with Bailey (1964), the individuals that identified the samples described in Stainforth (1966) included palynologists that were probably quite capable of distinguishing pollen and spores from altered volcanic glass. Therefore, it is likely that the Paruima and Cerro Venamo hornfels were contaminated with Mesozoic to Tertiary pollen and spores and that the particles were not misidentified volcanic glass or other non-biological materials. Contrary to the hopes of YECs, no one mentioned by Stainforth (1966) argued that the pollen and spores were from the Precambrian.

Dr. Silvestru's YEC Interpretation of the Origin of the Pollen and Spores

Since the 1960s, the controversy about microfossils in the Roraima Supergroup has disappeared from the peer-reviewed science literature. Although Silvestru (2012, p. 54) accuses the “scientific establishment” of avoiding this issue because it challenges their “evolutionary dogma”, he (p. 54) also states, probably correctly, that the current consensus among the “evolutionists” is that the pollen and spores are examples of contamination. Silvestru (2012) wants his opponents to believe that the hornfels could not have possibly been contaminated with pollen, that his interpretations of Genesis are superior to the radiometric dates associated the Roraima Supergroup, and that the scant information in a single brief 1966 paper by Stainforth threatens the validity of plant evolution and the geologic timescale.

Microfossils in Metamorphic Rocks

Silvestru (2012, pp. 54-55) claims that the “only argument” in favor of Mesozoic to Tertiary contamination is that metamorphism would have destroyed the pollen and spores. While the graph in Figure 1 and discussions of the metamorphic mineralogy and facies identifications in Silvestru (2012, p. 55) suggest that the metamorphism of the hornfels occurred at 500-700^oC, Beyer et al. (2015, p. 245) estimated much lower metamorphic temperatures of 300-350^oC for their andalusite-cordierite hornfels collected from other locations in the Roraima Supergroup. A review of standard metamorphic pressure and temperature diagrams (such as those in Figure 16.6, p. 420 in Philpotts and Ague 2009 and Figure 28-2, p. 565, in Winter 2001) indicates that metamorphic temperatures of 300-350^oC are too low for the formation of andalusite-cordierite hornfels and that the estimates of about 500-700^oC from Figure 1 of Silvestru (2012, p. 55) and a hornblende facies identification from the information in Silvestru (2012, p. 55) are more reasonable.

Silvestru (2012, p. 57) cites Schiffbauer et al. (2006), Hanel et al. (1999) and Zang (2007) to argue that organic microfossils can survive metamorphism. But, how well preserved are the microfossils discussed in these references and how might their preservations compare to the “well-preserved” microfossils observed in Stainforth (1966)? Silvestru (2012, p. 57) indicates that Schiffbauer et al. (2006) heated acritarchs (Dictyosphaera delicata and Shiuyousphaeridium macroreticulatum) to 500^oC over various lengths of time and noticed no graphitization. Acritarchs are not pollen or spores, but are Precambrian fossils that were probably eukaryotes.

Although Schiffbauer et al. (2006) indicate that no “features related to graphitization” were observed, Silvestru (2012, p. 57) does not mention that they also made the following statement:

“Preliminary Raman analysis reported here illustrates a decrease in D:G [disordered band to graphite band] ratios of heated acritarchs as compared to spectra of unheated acitarchs, suggesting that the heated samples are becoming more graphitized.”

Although the fossils were not completely graphitized at 500^oC as Silvestru (2012, p. 57) emphasizes, the preliminary analyses indicated that they were beginning to alter to graphite. Schiffbauer et al. (2006) is only an abstract and no details are presented on how long the samples were heated in this laboratory study. However, Schiffbauer et al. (2007, p. 700) and Zang (2007, p. 108) confirmed that the Schiffbauer et al. (2006) heating experiments lasted up to 125 days. In a later study, Schiffbauer et al. (2012) extended the laboratory heating times of Precambrian acritarch fossils to 250 days under both oxic and anoxic conditions. Although the acritarch fossils better survived heating under anoxic than oxic conditions, all of the fossils showed increased carbonization with time.

Silvestru (2012, p. 57) also claims that the duration of the heating studies in Schiffbauer et al. (2006) were “compatible with real cases of thermal metamorphism.” However, is 125 days of heating long enough to be “compatible with real cases of thermal metamorphism” as Silvestru (2012, p. 57) states? Are the 250 days of the Schiffbauer et al. (2012) studies even long enough to be “compatible with real cases of thermal metamorphism”? The answers are no. Temperatures in cooling plutons and their contact metamorphic aureoles may remain elevated for thousands of years or even longer (Winter 2001, pp. 417-418; Best 2003, p. 430; Philpotts and Ague 2009, pp. 511-583). Would the graphitization process have been completed and the microfossils destroyed at 500^oC in 10 years, 100 years, or longer under natural conditions involving metamorphism? Although the studies in Schiffbauer et al. (2006; 2012) demonstrate that microfossils may somewhat survive months of laboratory heating at 500^oC, Schiffbauer et al. (2007) investigated the origins of graphite particles from the Wutai Metamorphic Complex of northern China, which had been metamorphosed at a maximum metamorphic temperature of 513 +/- 50^oC. They concluded that the graphite particles might be microfossils, but because they were so extensively altered, their origin is inconclusive (Schiffbauer et al. 2007, p. 701). Schiffbauer et al. (2012, p. 403) further warn that non-biological particles can be difficult to distinguish from microfossils after metamorphism:

“Not only can morphological or biochemical signatures of life be distorted or even destroyed entirely by metamorphic processes, these same processes can generate abiotic but biologically mimicking doppelgängers.”

So, it’s doubtful that metamorphism at 500^oC would yield “well-preserved” microfossils.

Hanel et al. (1999), the second reference cited by Silvestru (2012, p. 57), is a palynological study of amphibolite-facies gneisses from Germany. Microfossils survived metamorphic temperatures that were as high as 580-710^oC (Hanel et al. 1999, p. 52). Although the microfossils could be identified as chitinozoans and compressed sphaeromorphic arcitarches based on their general shapes, they were completely graphitized and poorly preserved (Hanel et al. 1999, pp. 53, 54, 55). Hanel et al. (1999, p. 54) state:

“As expected, delicate structures important for taxonomic classification, such as, for example, spines and ornamentations, have been destroyed during graphitisation. Additionally, geometrical relationships important for taxonomic classification, such as width and length ratios of vesicles and necks or the form of the flexure between neck and body chamber, have changed through deformation.”

Hanel et al. (1999, p. 55) also make the following comments:

“During prograde metamorphism, all organic hydrocarbons that survived diagenesis will be irreversibly transformed to graphite.”

“Although completely graphitised, the original form of acritarchs and chitinozoans may still be recognisable; however, delicate structures important for taxonomic classifications are usually destroyed by graphitisation.”

Although the fossils described in Hanel et al. (1999) did survive metamorphism, Silvestru (2012, p. 57) fails to mention that they were entirely charred and not well preserved.

Silvestru (2012, p. 57) quotes Zang (2007) as indicating that the world’s oldest fossils (arcitarchs) in the Harris Greenstone Domain of South Australia survived metamorphism and several volcanic events. The fossil-bearing sediments were deposited about 2.52 billion years ago and experienced intermediate-level amphibolite-facies metamorphism at approximately 2.44 billion years ago (Zang 2007, p. 107). Metamorphic temperatures reached 600-700^oC (Zang 2007, p. 115). The microfossils in the metamorphosed rocks are altered and are best preserved in metamorphosed chert lenses. Zang (2007, p. 108) gives the following description of the organic materials in thin sections of the rocks:

“Most organic matter in the thin sections is graphitic and black, whereas the thin metachert lenses preserve some black to dark-brown organic remains.”

Although Zang (2007, p. 110) described the organic matter in the metachert as graphitic, some identifiable microfossils were found in the cherts (Zang 2007, p. 108). Zang 2007, p. 118) also notes:

“Chert or silica is always considered to be the best medium to preserve organic remains and protect them from metamorphic mechanical deformation and chemical damage.”

Although the fossils are extensively altered, some of them were identifiable because they were in the unusual situation of being protectively encased in chert.

Silvestru and Wieland (2011) also mention that Bernard et al. (2007) found “remarkably preserved” fossil spores in high-grade metamorphic rocks from the French Alps. However, Silvestru and Wieland (2011) do not mention the metamorphic temperatures were relatively cool. Although the metamorphism attained high pressures of 14 kilobars at burial depths of about 35 kilometers, temperatures only reached about 360^oC (Bernard et al. 2007, p. 257). A temperature of 360^oC is very close to the temperature range of 300-350^oC given by Beyer et al. (2015, p. 245) for their andalusite-cordierite hornfels, but is much lower than the more likely temperature range of 500-700^oC obtained from the information in Silvestru (2012, p. 55).

In each of the examples cited by Silvestru (2012) and Silvestru and Wieland (2011), host rock mineralogy and/or other relevant conditions did not resemble those in the Stainforth (1966) Roraima hornfels with their supposedly “well-preserved” pollen and spores. That is, the fossils in Dr. Silvestru’s references were only heated under laboratory conditions for a maximum of 125 days (Schiffbauer et al. 2006; Zang 2007, p. 108), were entirely altered to graphite by the metamorphism and were poorly preserved (Hanel et al. 1999), were encased in protective chert (Zang 2007) that was not present in the Roraima hornfels or were likely metamorphosed at much lower temperatures (Bernard et al. 2007) than the hornfels discussed in Stainforth (1966) and Silvestru (2012).

Other studies not mentioned in Silvestru (2012) and Silvestru and Wieland (2011) also indicate that if microfossils survive intense metamorphism, they are inevitably altered and do not tend to be “well-preserved.” For example, Sarana and Kar (2011) described the petrology and palynology of Indian coals that had been metamorphosed by a dolerite (diabase) dike. According to Sarana and Kar (2011, p. 164), the presence of pyrite in the coals indicates that the metamorphism did not exceed 500^oC. Sarana and Kar (2011, p. 161) conclude:

“The palynological investigation of unaffected coals shows the presence of a number of well-identified spores and pollen. However, very few palynomorphs could be recovered from coals located close to the intrusive as the pollen/spores were found to be charred beyond recognition.”

In an example published after Silvestru (2012) and Silvestru and Wieland (2011), Heward and Penney (2014) described fossil spores and pollen in greenschist rocks from Oman as being “highly carbonized” and “poorly preserved”, but still identifiable. Greenschist rocks form at lower temperatures than the hornblende-facies hornfels of the Roraima Supergroup. Heward and Penney (2014, p. 289) also made the following statement about the condition of their samples:

“At the levels of carbonization shown by the samples, it is difficult to distinguish genera let alone attempt speciation.”

While Mesozoic and Tertiary pollen that entered the hornfels after metamorphism could be “well-preserved”, how likely is it that the pollen and spore fossils in the Roraima Supergroup hornfels could be described by Stainforth (1966) as “well-preserved” if they underwent metamorphism at about 500-700^oC as indicated by the graph in Figure 1 and discussions of the metamorphic mineralogy and facies identifications in Silvestru (2012, p. 55)? Certainly, the phrase “well-preserved” is pretty subjective and vague. Without photographs and better descriptions of the conditions of the pollen and spores, we simply do not know how “well preserved” the samples discussed in Stainforth (1966) really were. Nevertheless, the following comments mentioning “uncompressed preservation” by J.W. Funkhouser in Stainforth (1966) further suggest that the pollen and spores entered the hornfels long after the metamorphism and were not charred to graphite as would be expected by hornblende-facies hornfels metamorphism:

“J.W. Funkhouser (Bogotá) considers the pollen indigenous to the samples he processed but claims an age no older than Miocene, and probably younger; he notes similarities to the flora of the Mesa Formation (Pliocene-?Pleistocene) of Colombia, presence of pollen of the Compositae, and an uncompressed preservation highly unusual except in young sediments.”

Without additional information on the identities of the pollen and spores described in Stainforth (1966) and how “well-preserved” they really were, the YEC claims in Silvestru (2012) are simply unproven speculation.

Other Misunderstandings and Errors in Silvestru (2012)

Sill Formation

Silvestru (2012) clearly wants to demonstrate that the diabase sills were injected into wet sediments under a YEC scenario. He also wants to discredit the idea that the sills were emplaced in very old sedimentary rocks and that the hornfels were contaminated with pollen and spores nearly two billion years later. In his efforts to achieve these goals, Silvestru (2012) makes a number of errors and misunderstandings about geology. For example, Silvestru (2012, p. 57) contains the following loaded question:

“How does a 400-m dolerite intrusion ingest and digest a hard sedimentary rock over many horizontal kilometres, while remaining perfectly parallel with the host rock and chemically ‘pure’?”

Magmas that form sills tend to intrude into the planes of weakness between layers of well-lithified sedimentary and volcanic rocks, and these layers and planes of weakness may extend horizontally over vast distances. Only rocks in close contact with the magma would melt and the amount of melting would depend on the temperature and fluid content at the contact (Winter 2001, pp. 417-418; Philpotts and Ague 2009, pp. 414-417). More distant rocks would experience contact metamorphism, where the rocks are “baked” to hornfels, but not to the point of melting. Besides melting and breaking rocks, Silvestru (2012, p. 57) fails to mention that magmas may also lift overlying rocks as they intrude (Hogan et al. 1998). So, a 400-m dolerite (diabase) sill did not need to melt and consume large volumes of rock to become emplaced, it could have squeezed into, compressed and lifted many of the rocks during emplacement.

Reis et al. (2013, p. 186) provide geochemical evidence that the plutons associated with the Roraima Supergroup were contaminated with continental crustal rocks. It is not surprising that hot magmas passing through a thick crust would assimilate chemicals from the crust. So, the chemistry of the dolerite (diabase) plutons was altered and the plutons are not “chemically pure” as Silvestru (2012, p. 57) claims.

Without providing any references, Silvestru (2012, p. 57) also claims that no sills have been associated with historic volcanic eruptions. Although sills and other plutons are injected kilometers below the surface and are not readily accessible, geophysical methods have detected sills currently forming in volcanically active areas (as examples: Yellowstone [Chang et al. 2010] and Iceland [Hjaltadóttir et al. 2015]).

Finally, Silvestru (2012, p. 57) suggests that the “problems” with sill emplacement would be greatly diminished if unbounded water-rich sediments had been present and if the plutons displaced rather than ingested these sediments. However, unbounded (presumably surface) wet sediments are no solution to any problems associated with sill emplacement. By definition, sediments are unlithified; that is, they lack cementation and consist of loose particles with relatively high surface areas. Sills and dikes inject into linear fractures, faults and well-established bedding planes, which would be absent in loose sediments. Contrary to Silvestru (2012, p. 57), sediments because of their lack of cementation and high-surface area particles would have a greater tendency to be torn apart and assimilated in magmas than well-indurated sedimentary rocks even with bedding planes. Also, if the unbounded sediments were wet, why would hot and dry mafic magmas form relatively quiet sills in them rather than producing explosive phreatic (steam) eruptions and collapsing calderas?

Cross-cutting relationships between mineral grains in thin sections are used to determine the sequence of mineralization events in rocks. Beyer et al. (2015, pp. 231-232) identified three quartz cement phases in the Roraima Supergroup. While Stainforth (1966) indicates that clay minerals and chlorite were not detected by X-ray diffraction in his hornfels, Beyer et al. (2015, p. 232) used optical microscopy to conclude that the formation of the quartz cements was followed by the alteration of feldspars to form kaolinite clay and white mica cement in many of their Supergroup samples. All of these cementation events occurred before the contact metamorphism. So, why would cross-cutting relationships indicate that quartz and other cements were extensively present in the rocks of the Roraima Supergroup before metamorphism if the rocks had actually been wet sediments and not cemented sedimentary rocks when the intrusions occurred as Silvestru (2012, p. 57) claims?

Permability of Seemingly Impermeable Rocks

Silvestru (2012, p. 58) quotes Stainforth (1966) and describes the hornfels as being impermeable, which included an “evaluation” of the density of the rocks by hitting them with a hammer. Although a rock may appear or “sound” impermeable on a macroscopic scale, it may contain microscopic fractures and openings that allow for the inclusion of pollen and spores. Even seemingly impermeable and unfractured metamorphic and igneous rocks commonly have very low, but measurable permeabilities of 10^-13 – 10^-16 square centimeters (cm²) or lower (Freeze and Cherry 1979, p. 29). Thin-section and other microscopic examinations of any pollen- and spore-bearing hornfels are required to determine if the pollen and spores are located in the matrix of the rocks or concentrated in fractures and other microscopic openings as T. van der Hammen in Stainforth (1966) concluded.

Groundwater Interactions with the Roraima Hornfels

As a karstologist, Silvestru (2012, pp. 57-58) discusses in some detail the silicate karst in the Mataui Formation of Mt. Roraima, Venezuela, and its groundwater hydrology (Figures 1 and 2). Silvestru (2012, p. 58) denies that groundwater would be able to penetrate deep enough to form aquifers below the Mataui Formation karst. Actual field and laboratory results from Mecchi et al. (2014) and Sauro (2014) indicate that groundwater erosion was extensive in the Mataui Formation caves of Mt. Roraima, including the opening of deep fractures in the rocks, called simas or grietas. Mecchia et al. (2014, pp. 117, 118, 119, 132) also refer to high weathering rates in the underlying arkosic sandstones, which would likely include the Umaipé and Kukenán formations. Kukenán is probably an alternative spelling for the Cuquenan Formation, which Silvestru (2012, p. 55) suggests is the source of the Stainforth (1966) hornfels (Figure 2). So, it’s likely that the Umaipé and Cuquenan formations are far more permeable and wet than what Silvestru (2012) admits.

While Silvestru (2012, p. 57) claims that water acidity should be lost after 10-15 meters of infiltration into the subsurface, the water in the caves of the Mataui Formation is acidic with general pH values of 3-6.5 (Mecchi et al. 2014, pp. 124, 125). Considering the very wet climate in the area and the evidence of extensive fracturing, weathering and groundwater flow in Mecchi et al. (2014) and Sauro (2014), the speculation in Silvestru (2012, p. 58) that groundwater could not enter the rocks underlying the caves is doubtful.

After discussing the groundwater hydrology at Mt. Roraima, Silvestru (2012, p. 58) claims that pollen- and spore-laden groundwater could not have passed through the thick sills and formations to reach the Cuquenan Formation that he believes contained the Stainforth (1966) hornfels. However, even if the hydrology of Mt. Roraima in Silvestru (2012) is correct, the groundwater hydrology of Mt. Roraima is largely irrelevant to the hydrology of the Stainforth (1966) hornfels outcrops at Paruima and Cerro Venamo, Guyana. Mt. Roraima has an elevation of 2,810 meters above mean sea level and the mountain is located about 83 km south, southeast of Paruima (elevation 538 meters) and about 114 km southeast of Cerro Venamo (elevation 1,890 meters) (Figure 1). Because the pollen- and spore-bearing hornfels at Paruima and Cerro Venamo were collected from outcrops, any overlying rocks would have been thin or absent due to erosion. So, currently, the outcrops are readily accessible to surface and groundwater. Nevertheless, would groundwater have necessarily passed through thick overlying formations during the Tertiary to contaminate the hornfels with pollen and spores? Although large volumes of water can infiltrate into the Earth’s crust (Best 2003, pp. 488-489), there is no reason to believe that the Paruima and Cerro Venamo hornfels outcrops would have been buried under thick rocks during the entire Mesozoic to Tertiary and isolated from groundwater as Silvestru (2012, p. 58) indicates. Mecchia et al. (2014, p. 118) states that the region was uplifted to its current elevation as early as about 110 million years ago (late Early Cretaceous) as a consequence of the opening of the South Atlantic Ocean during the breakup of the Pangaea Supercontinent. While the current denudation rate on the especially hardened crusts on the top of Mt. Roraima is very low at only about 1 mm per 1,000 years (Mecchia et al. 2014, pp. 118, 130; Brown et al. 1992), the presence of rivers along with the heavy rainfall in the Paruima and Cerro Venamo regions would have easily eroded the overlying rocks during the millions of years during the late Mesozoic and Tertiary, and allowed Tertiary groundwaters to infiltrate the hornfels and possibly contaminate them with pollen and spores.

In my essay (Henke 2005) questioning YEC claims of pollen in the Precambrian and Paleozoic rocks of the Grand Canyon, I suggested that the possibility of pollen contamination might be evaluated by taking rock samples from deep well cores. Efforts could then be made to look for pollen in the subsurface away from modern rivers, joints, and faults. It’s interesting that pollen and spores were found in surface outcrops at Paruima and Cerro Venamo according to Stainforth (1966), but that no microfossils were reported in the numerous thin sections of deeper rock core samples taken by Beyer et al. (2015) near Mt. Roraima.

Limonite Formation

Although he described the Roraima hornfels as being “unweathered”, Stainforth (1966) identified materials on the bedding planes of the rocks as “limonite”, which is a common group of iron oxyhydroxide compounds that result from the alteration of iron minerals. Silvestru (2012, p. 58) argues that if limonite formation has been occurring since at least the Tertiary, the bedding planes should also be covered with clay minerals. However, Silvestru (2012, p. 58) found no evidence of clays detected by X-ray diffraction or in thin sections from the literature on Roraima hornfels that he reviewed. As an alternative explanation, Silvestru (2012, p. 58) argues that the limonite is syngenetic and resulted from hydrothermal metamorphism of olivines in the dolerites (diabases).

The superficial statements in Stainforth (1966) do not provide enough information to support the conclusions in Silvestru (2012, p. 58). Although Stainforth (1966) indicates that no clay minerals were detected by X-ray diffraction in the hornfels, it’s likely that the bedding planes had been removed from the samples before these analyses. Furthermore, limonites are amorphous materials and cannot be identified with X-ray diffraction methods anyway (Klein and Hurlbut 1999, pp. 661, 159-160). Unfortunately, Stainforth (1966) does not state how the “limonite” was identified, distinguished from goethite and other iron oxyhydroxide minerals and whether any characterization methods were extensive enough to determine if clay or other minerals were absent from the “limonite” on the bedding planes. If the “limonite” was simply identified by color or other visual inspections, which was often the case 50 years ago before the development and commercialization of advanced analytical methods, then it is very possible that the “limonite” could actually be goethite or another iron oxyhydroxide. Even if the layer is limonite, clay minerals could also be present (Krauskopf and Bird 1995, p. 334). Without performing detailed characterizations, iron-stained clay minerals mixed with limonite or goethite may not be distinguishable. The presence of limonite, other iron compounds and/or clay minerals on bedding planes would depend on groundwater flow, pH, Eh, the zero points of charge, and other factors (Krauskopf and Bird 1995, pp. 135-162). It’s certainly possible for iron weathering products to stain or accumulate on the surfaces of rocks with or without the presence of clay minerals.

The detailed studies in Beyer et al. (2015) contradict the speculations in Silvestru (2012, p. 58) on the origin of limonite and the supposed absence of clay minerals on the bedding planes of the Roraima Supergroup hornfels. Based on cross-cutting relationships with other minerals as seen in thin sections, Beyer et al. (2015, pp. 236, 246, Figure 5, p. 235) describes limonite forming with kaolinite clay long after the metamorphism of the Supergroup. The limonite and kaolinite also likely formed within 80 meters of the modern erosional surface and probably from recent lateritic weathering involving low-temperature meteoric water (Beyer et al. 2015, pp. 246, 248). In other words, at least for the Roraima Supergroup rocks in Beyer et al. (2015), the limonite is a weathering product resulting from rainwater-fed groundwater and not from hydrothermal metamorphism as advocated by Silvestru (2012, p. 58). Because of the lack of suitable mineralogical details in Stainforth (1966), there is simply not enough evidence to propose that any “limonite” on the bedding planes of the Stainforth (1966) hornfels had an alternative hydrothermal origin. If individuals want to argue that the results in Beyer et al. (2015) somehow do not apply to the Stainforth (1966) samples, then they must obtain additional pollen- or spore-bearing hornfels from the Roraima Supergroup and perform adequately detailed characterization studies that are comparable to the efforts of Beyer et al. (2015). For now, the most reasonable explanation is that both the Stainforth (1966) and Beyer et al. (2015) Roraima Supergroup hornfels were weathered by same low-temperature groundwater processes described in Beyer et al. (2015).

Consensus on Pollen and Spores in the Roraima Supergroup

Silvestru (2012, p. 58) also notes that widespread pollen has not been reported in other Roraima Supergroup rocks from the region. Except for the brief summaries reported in Stainsforth (1966) and related articles, there have been no reports of pollen and spores in other samples of the Roraima Supergroup. Although an absence of evidence is not necessarily evidence of absence, Beyer et al. (2015) made thin sections of numerous samples from the Roraima Supergroup and did not report finding any fossils.

Silvestru (2012) clearly believes that scientists should take the Roraima studies from the 1960s seriously because it threatens biological evolution and the geologic time scale. Unfortunately for YECs, the vast majority of secular scientists see YEC arguments on the Roraima Supergroup and other issues as weak and unworthy of further responses. The best case for pollen and spores in the Roraima Supergroup is in Stainforth (1966) and the brief article contains no photographs of these microfossils, lacks other critical details, and simply provides no worthwhile evidence that threatens the validity of plant evolution or the geologic time scale. Even YEC Snelling (2009, p. 737, Footnote 15) expresses skepticism about “out of place” pollen. He cites Stainforth (1966) and refers to it and similar claims of “out of place” pollen from the Grand Canyon as not “equivocally documented.”

Overall, researchers can reasonably conclude that Allen (1967) was right and that the “microfossils” in Bailey (1964) are actually volcanic glass and that the pollen and spores in the Stainforth (1966) samples are Tertiary and possibly Mesozoic contamination. Whether YECs are willing to accept it or not, most scientists do not consider biology, astronomy, geology, chemistry and physics to be under siege from a handful of YECs. If YECs want to use their meager resources to perform a more thorough investigation of pollen and spores in the Roraima Supergroup, I would encourage them to take a lot of photographs, use every modern and relevant analytical instrument that is available to determine the conditions and identities of the host rocks and any pollen and spores that they may find, and to publish all of their results, preferably in a respectable peer-reviewed journal. Beyer et al. (2015), Mecchia et al. (2014) and Sauro (2014) are good examples of the level of detail that is required. Nevertheless, YECs would better serve their agenda by spending their limited time and resources on finding non-ambiguous evidence of in-place dinosaur, human remains, and other macrofossils in the Precambrian, which, unlike microfossils, would not be highly susceptible to misinterpretations and contamination.

Conclusions

In his paper, Bailey (1964) never identified his supposed Roraima “Formation” microfossils as pollen or spores. Allen (1967) reasonably states that the supposed microfossils mentioned in Bailey (1964) are actually partially altered particles of volcanic glass. The situation in Stainforth (1966) is very different. Palynologists were involved in that study. However, contamination is the most likely explanation for the Tertiary and perhaps Mesozoic pollen in the Stainforth (1966) Roraima Supergroup hornfels. Extensive studies of the Roraima Supergroup by Beyer et al. (2015) and others have not changed that conclusion.

The literature indicates that pollen and other microfossils may survive metamorphism, but they are usually severely altered, especially in the likely range of metamorphic temperatures for the Roraima Supergroup hornfels, which is 500-700^oC according to information in YEC Silvestru (2012, p. 55). Stainforth (1966) contains no photographs of the Roraima pollen and spores. Quotations in Stainforth (1966) and the single phrase that the pollen and spores were “well preserved” suggest a lack of metamorphic alteration. Nevertheless, the descriptions and documentation in Stainforth (1966) are simply too brief, lacking in crucial details and too vague for Silvestru (2012) and other YECs to make any reasonable case that pollen and spores were actually deposited in Precambrian sediments and that these results invalidate botanical evolution and the geologic time scale. Rather than attempting to redo the Roraima study or continuing to make irrational accusations of a conspiracy of silence among scientists who refuse to accept the poorly documented claims in Bailey (1964) and Stainforth (1966), Silvestru (2012) and his allies need to spend their limited resources on finding solid evidence of in-place dinosaur, human remains, and other macrofossils in the Precambrian. Microfossils simply have too great of a potential to be misidentified by non-specialists or contaminate older rocks that appear or “sound” “impermeable.”

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