Using Google Earth terrain maps, Mr. Thomas Lee Elifritz found 
what he speculates might be impact crater of the “12,900 BP 
Younger Dryas Clovis cometary ice sheet impact” (Anonymous 
2011, Elifritz 2009a, 2009b). His interpretation is based solely 
upon a vague circular feature, which is centered around 
49˚ 10’ 41” N., 88˚ 43’ 9” W. and is about 25 to 26 km in 
diameter. The edge of this feature lies at the southern end of 
Black Sturgeon Lake, along cliffs just north and east of Nonwaith 
Lake, along a well-defined ridge, Fox Mountain, just east and 
north of Disraeli Lake, and through middle of Black Mountain 
Lake. 

As noted by Hart and Magyars (2004), this area was mapped 
by Coates (1972) at a scale of 1:63 360. This geologic map 
included an interpreted geological section. Later, Sutcliffe (1982) 
mapped the geology of the northeast part of this area from 
immediately south of Lake Nipigon to the southern edge of 
Black Sturgeon Lake at a scale of 1:50 000. Also, various 
studies, i.e. Sutcliffe (1987), Hart and McDonald (2007), 
Heaman et al. (2007), and Hollings  et al. (2007) have 
investigated in detail the areal intrusive rocks, Nipigon 
diabase sills and ultramafic intrusions of the Disraeli and 
Seagull–Lecky lakes areas. The sedimentary rocks of the 
Sibley Group, which underlie this area have also been studied 
by various investigators, i.e. Franklin et al. (1980), Chile 
(1986), Regale (2003), and Frolic and Zanies (2011).  Recent 
geologic mapping, reports, and talks, Hart and Magyars 
(2004), Magyars et al. (2004), Hart 2005a, 2005b), and Hart 
and Olson (2005) provide very detailed discussion, geologic 
maps, and subsurface cross-sections of the northern  Black 
Sturgeon River–Disraeli Lake region based upon detailed 
field work conducted during the summer of 2003 and existing 
subsurface data. Finally, frequent mineral exploration and 
prospecting has occurred within this area. This exploration has 
created a collection of lithologic logs of and actual cores from 
numerous drill holes from which cross-sections of the subsurface 
geology of this area have been created by Coates (1972), 
Hart and Magyars (2004), Magyars et al. (2005), Hart
and Thompson (2007) and others.

The above research provide a wealth of information about
the surface and subsurface geology of this hypothesized 
extraterrestrial impact structure. This feature, including its
northern, southern, and western edges, are underlain by 
undeformed, relatively flat-lying sedimentary rocks of the 
Sibley Group (Coates 1972;Cheadle, 1986; Regale, 2003; 
Hart and Magyars, 2004; Hart, 2005a; Magyars et al., 2005). 
These sedimentary rocks are interlayered with thick, concordant 
Nipigon Diabase Sills (Hart, 2005a, 2005b; Hart and Magyars, 
2004; Magyars et al., 2005; Hart, 2007; Easton et al., 2007; 
Hollings  et al., 2007). The northeastern edge of this feature 
consists of a thick, relatively flat-lying, and undeformed 
diabase sill, which have intruded metasedimentary rocks 
and granitic and tonalite intrusives of the Quetico Subprovince 
(Coates, 1972; Hart, 2005a; Hart and Magyars, 2004; 
Magyars et al., 2005).

Both sedimentary rocks of the Sibley Group and the Nipigon 
Diabase Sills exhibit a lack of any deformation that can be 
associated with the entire circular feature hypothesized 
to be an impact crater. These strata are flat-lying to slightly
dipping. They are disturbed only by regional north and 
northwest-trending faults that are interpreted to have locally
created a block-faulted asymmetric basin or graben. These 
faults are considered the result of the reactivation of earlier 
Archean structures during the Late Proterozoic (Coates, 
1972; Franklin et al., 1980; Hart and Magyars, 2004; 
Magyars et al., 2005).

Only along the northeast rim is faulting even roughly 
associated with the rim of this feature. The rim is not the 
direct result of fault movement. Rather, its is the result 
of differential erosion of less resistant sedimentary rocks 
of the Sibley Group and more resistant metasedimentary 
and tonalite intrusives of the Quetico Subprovince on either 
side of faults. In addition, the faults are high angle faults 
with orientations and dips typical of regional faulting 
(Coates, 1972; Franklin et al., 1980; Hart and Magyars, 
2004; Magyars et al., 2005). These faults lack the 
characteristics of those exhibited by extraterrestrial 
impact structures (Melosh 1989).

Furthermore, There is a complete lack of any evidence for 
any recognizable structural control of the western and 
southern edge of this feature, which is composed of roughly 
arcuate ridges, Fox, Wolf, and Eagle mountains. The 
geologic mapping and cross-sections of Coates (1972), 
Hart 2005a, Hart and Magyars (2004), Magyars et al. 
(2005), and Hart and Thompson (2007) show that they 
consist of relatively flat-lying and undeformed sedimentary 
rocks of sedimentary rocks of the Sibley Group and 
interlayered sills of the Nipigon Diabase. There is a 
complete absence of any deformation that could be 
associated with an extraterrestrial impact (Melosh 1989). 
If there is structural control to these ridges, it is the
result something considerably more subtle and cryptic 
than an extraterrestrial impact.

Concerning the circular feature, which Elifritz (2009a, 
2009b) proposed to be a possible Younger Dryas Impact, 
there exists sufficient information to make a preliminary 
evaluation of this hypothesis. The undeformed and 
relatively flat-lying nature of the sedimentary strata and 
interlayered diabase sills readily refutes any idea that this 
feature is an impact structure any sort or age given the 
25-km diameter of this feature. An extraterrestrial origin 
of this feature is further refuted by the lack of any 
significant consistent relationship between regional 
faults and the feature and the age of the faulting. 
Despite its roughly circular shape, it appears that this 
circular feature is combined result of past differential 
weathering and glacial and glacial and meltwater 
erosion of the Proterozoic sills and Sibley Group 
metasedimentary strata that has been  influenced by 
Proterozoic faulting and possible cryptic structural 
controls.

If anything, this feature is most likely a example of the 
problems with relying entirely on terrain maps (digital 
elevation models) as a basis for identifying extraterrestrial 
impact crates. It shows that existing geological research 
also needs to be consulted before proposing any circular 
feature as an impact crater. This feature is likely a 
classic example of Riemold (2007)’s “Impact Crater 
Bandwagon.”

References Cited,

Anonymous (2011) Clovis Comet Crater? The Cosmic Tusk 
(Oct. 10, 2011) http://cosmictusk.com/clovis-comet-crater .

Chile, B. A., 1986, Alluvial-playa sedimentation in the lower 
Keweenawan Sibley Group, Thunder Bay District, Ontario. 
Canadian Journal of Earth Science. vol. 23, pp. 527-542.
http://www.nrcresearchpress.com/doi/abs/10.1139/e86-053

Coates, M. E., 1972, Geology of the Black Sturgeon River area, 
District of Thunder Bay. Geoscience Report no. 98, Ontario 
Department of Mines and Northern Affairs, Toronto, Ontario. 41p.

Easton, R. M., T. R. Hart, P. Hollings, L. A. Heaman, C. A. 
MacDonald, and M. Smyk, 2007, Further refinement to the 
timing of Mesoproterozoic magmatism, Lake Nipigon region, 
Ontario. Canadian Journal of Earth Sciences. vol. 44, 
pp. 1055-1086.
http://www.nrcresearchpress.com/doi/abs/10.1139/e06-117
http://www.nrcresearchpress.com/toc/cjes/44/8

Elifritz, T. L., 2009a, Younger Dryas Cometary Impact Crater Near 
Lake Nipigon. Unpublished manuscript dated March 20, 2009.
http://www.scribd.com/doc/68237039/Clovis-Comet-Crater
http://webpages.charter.net/tsiolkovsky/Clovis_Comet_Crater.pdf
http://webpages.charter.net/tsiolkovsky/Clovis_Comet_Crater.jpg

Elifritz, T. L., 2009b, Darwin’s Valentine - A Cometary Impact 
Remnant Transposed Upon Glacial Terrain Near Lake Nipigon? 
Unpublished manuscript dated February 28, 2009.
http://webpages.charter.net/tsiolkovsky/Darwin's_Valentine.pdf
http://webpages.charter.net/tsiolkovsky/Darwin's_Valentine.jpg

Frolic, P., and K. Zanies, 2011, Sedimentology of a wet, 
pre-vegetation floodplain assemblage. Sedimentology.
Article first published online, Oct. 20, 2011
DOI: 10.1111/j.1365-3091.2011.01291.x
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-3091.2011.01291.x/abstract

Franklin, J. M., W. H. McIlwaine, K. H. Poulsen, and R. K. 
Wanless, 1980, Stratigraphy and depositional setting of the
Sibley Group, Thunder Bay District, Ontario, Canada. Canadian 
Journal of Earth Sciences. vol. 17, pp. 633-651.
http://www.nrcresearchpress.com/doi/abs/10.1139/e80-060
http://www.nrcresearchpress.com/toc/cjes/17/5

Hart, T.R., 2005a, Precambrian geology of the southern Black 
Sturgeon River and Seagull Lake area, Nipigon Embayment, 
northwestern Ontario. Open File Report no. 6165, Ontario 
Geological Survey, Toronto, Ontario. 63 pp.
http://www.geologyontario.mndmf.gov.on.ca/mndmfiles/pub/data/imaging/OFR6165/OFR6165.pdf

Hart, T. R., 2005b, Lake Nipigon Regional Geoscience Initiative: 
Proterozoic and Archean Geology of the Southern area of the 
Western Nipigon Embayment. Ontario Geological Survey, poster, 
Northwest Mines and Minerals Symposium, Thunder Bay, 
Ontario, April 5-6.
http://www.mndm.gov.on.ca/mines/ogs/Posters/OEGS_2004/Hart_OEGS_2004.pdf

Hart, T. R., and Z., Magyars, 2004, Precambrian geology of the 
northern Black SturgeonRiver and Disraeli Lake area, Nipigon 
Embayment, northwestern Ontario. Open File Report no. 6138, 
Ontario Geological Survey, Toronto, Ontario. 56p.
http://www.geologyontario.mndmf.gov.on.ca/mndmfiles/pub/data/imaging/OFR6138/OFR6138.pdf

Hart, T. R., and C. A. McDonald, 2007, Proterozoic and 
Archean geology of the Nipigon Embayment: implications for 
emplacement of the Mesoproterozoic Nipigon diabase sills 
and mafic to ultramafic intrusions. Canadian Journal of Earth 
Sciences. vol. 44, pp. 1021-1040.
http://www.nrcresearchpress.com/doi/abs/10.1139/e07-026
http://www.nrcresearchpress.com/toc/cjes/44/8

Hart, T.R., and Olson, A. 2005. The Precambrian geology of 
the south Black Sturgeon River – Seagull Lake area, Geological 
Cross Sections, Nipigon Embayment, Northwestern Ontario. 
Preliminary Map no. P.3563, scale 1:50,000, Ontario Geological 
Survey, Toronto, Ontario.
http://www.geologyontario.mndmf.gov.on.ca/mndmfiles/pub/data/imaging/P3563/P3563.pdf

Magyars, Z., T. R. Hart, P. Frolic, R. Metsaranta, G. J. Heggie,
P. Hollings, and A. Richardson, 2004, Northern Black Sturgeon 
River area geological cross-sections, Nipigon Embayment, 
northwestern Ontario. Preliminary Map no. P.3540, scale 
1:50 000. Ontario Geological Survey, Toronto, Ontario.
http://www.geologyontario.mndmf.gov.on.ca/mndmfiles/pub/data/imaging/P3540/P3540.pdf

Melosh, H. J., 1989, Impact cratering : a geologic process.
Oxford University Press, Oxford, United Kingdom. 245 pp.

Reimold, W. U., 2007, The Impact Crater Bandwagon (Some 
problems with the terrestrial impact cratering record) 
Meteoritics & Planetary Science. vol. 42, no. 9, pp. 1467-1472. 
http://digitalcommons.arizona.edu/objectviewer?o=uadc://azu_maps/Volume42/Number9/p1467-1472

Regale, B., 2003, The Sibley Group: a lithostratigraphic, 
geochemical and paleomagnetic study; unpublished MS.
thesis, Lakehead University, Thunder Bay, Ontario, 254 p.

Sutcliffe, R. H., 1982, Precambrian geology of the Wabigoon–
Quetico Subprovince boundary, Orient Bay sheet, Thunder Bay 
District. Preliminary Map no. P.2531, scale 1:50 000, Ontario 
Geological Survey, , Toronto, Ontario.

Sutcliffe, R.H. 1986. Proterozoic rift related igneous rocks at 
Lake Nipigon, Ontario. unpublished PhD thesis, University of 
Western Ontario, London, Ontario, 325p.

Yours,

Paul H.
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