Back to LINKS IMPACTITES
WHEN BIG THINGS STRIKE THE EARTH ...
THE ENIGMATIC SUDBURY STAR WOUND
photos by Roman Jirasek
Astrobleme ... an ancient weathered impact structure meaning "star wound." The immense
Sudbury ringed structure is precisely that. More precisely, it is the aftermath remnants of a wound
resulting from a direct blow delivered courtesy of one of the largest meteorites ever to have
touched down on this pelted planet.
When two worlds collided ... Approximately 1.87 billion years ago, give or take a few millennia,
a cataclysmic event of almost unfathomable proportions took place a few kilometers north of
present day Sudbury, Ontario, Canada.
This event, involving a gigantic nine kilometer diameter space-invader traveling at 30 kilometers
per second, slamming into the earth with an impact force equivalent to detonation of several billion
tons of TNT, caused a ring of mainly blast debris and fallout material to form around the upper
portions of its original crater and one of the world's richest and most diverse metal, breccia and
mineral deposits to be buried below the structure as its eternal legacy. Thus the tale of "the basin"
begins.
In order to gain a greater understanding of the scope and sheer magnitude of the catastrophic
Sudbury occurrence and put it into perspective with a current event of similar scale, the following
facts should be taken into consideration.
The kinetic energy transfer & release explosion, the cosmic bomb effect, so to speak, caused by
the Sudbury superimpactor plowing full-speed into solid rock would literally make the nuclear
device that leveled Hiroshima seem like a firecracker in comparison. The concussion wave
traveling rapidly outward in all directions following the blast in modern times would completely
wipe out and erase all people, places and things, by conservative estimates, within a 500 mile
radius of ground zero.
The intense heat generated by the impact would cause at least several thousand cubic miles of
primordial, volcanic gas, sulfur, CO & CO2 rich, oxygen poor "air" surrounding the cosmic
contact zone to spontaneously ignite. The jolt resulting from an equivalent impact taking place just
north of present-day Sudbury would easily and noticeably be felt across all of Canada, Alaska and
the rest of the continental U.S.A. Seismographs on the opposite side of the earth would record the
event, and finally a long, dark, cold winter would begin to set in.
A scary scenario to say the least, however, it is accurate, realistic and unfortunately a very
potentially possible one in store for this planet at some point in time, between the near and distant
future. Such a scenario has happened before and all indications are that, sooner or later, it will
happen again. The silver lining to this likely lethal dark cloud is that research and contingency
planning is currently underway and progress is being made in efforts to avert such scenarios by
diverting or destroying any large object or objects posing the threat of direct collision with the
earth.
Sudbury Astrobleme Specimens;
Their History, Mineralogy and Origin -- Unique &
seldom seen ... containing a wide variety of rare & valuable minerals & elements, Sudbury
astrobleme meteorite impact specimens are amongst the finest & most interesting meteorite related
materials this planet has to offer. The story of their mystery shrouded historic past, their
composition and awesome origin is as interesting as it is fascinating. This entirely mesmerizing tale
-- which is already begun -- will now move on to the subject of metals, minerals & elements of the
Sudbury structure and then be followed up by an interwoven blend of facts, figures and general
information relating to the history and origin of the structure & its treasures.
METALS, METALLIC & SILICATE MINERALS OF THE SUDBURY
ASTROBLEME
Metals -- Gold Silver Platinum Palladium Nickel Copper Iron
Main Metallic Minerals -- Pyrrhotite (4 varieties) Pyrite (5 varieties) Pentlandite (4 varieties)
Chalcopyrite (3 varieties) Cubanite Ilmenite Magnetite
Less Common Metallic Minerals -- Bornite Valleriite Sphalerite Stannite Violarite Marcasite
Millerite Hematite Native Gold (Electrum) Native Silver Hessite Galena Parkerite Tetradymite
Native Bismuth Chalcocite Molybdenite Tetrahedrite Smaltite Danaite Native Copper Cassiterite
Iridium Tellurium Rhodium Ruthenium
Nickel Arsenic Bearing Minerals -- Gersdorffite Niccolite Maucherite
Minerals of the Precious Metals and their Associates -- Sperrylite Michenerite Froodite
Non-Metallic Minerals -- Gangue minerals, inclusions and products of wall rock alteration
Pseudotachylite Shocked and Regular Quartz Carbon Carbonates Fullerine Anthraxolite Graphite
Biotite Amphiboles Actinolite Hornblende Hastingsite Garnet Almandine Zircon Pyroxenes
Hypersthene Olivine Peridot Augite Chlorite
Cobalt and Selenium -- as neither of these elements occur alone in individual mineral
compounds but are distributed in solid solution in many of the common minerals, they require
separate consideration. Cobalt is present in all four of the major metallic minerals associated with
the Sudbury astrobleme. Within pentlandite, cobalt content averages 1 percent, while in pyrrhotite,
pyrite and chalcopyrite, cobalt represents only a fraction of a percent. Selenium is also present in
all four major metallic minerals, with chalcopyrite as the better host bearing an average selenium
content of 80 ppm, with the others each averaging in the 50-60 ppm range. Selenium is regarded
as a substitute for some of the original sulfur in the Sudbury sulfides.
A large portion of the afore-mentioned metals and rare metallic as well as silicate minerals are
found in the form of what are referred to in general terms as Sudbury sulfides. They occur as
several distinct varieties (types) seemingly randomly throughout the Sudbury astrobleme area and
end abruptly beyond the outer reaches of the structure. Sulfide varieties or types are --
disseminated, zoned or segregated, crystallized, injected, and brecciated.
Each of these main varieties or types have sub-classifications and quite often contain a mix of
minor amounts of one or more of the other main varieties within them. As an example, a breccia
specimen from one Sudbury astrobleme area mine may contain up to thirty percent disseminated
sulfide while a breccia sample from another mine from the same area may contain thirty percent
crystallized sulfide including the massive crystallized subtype.
Metal-Rich Breccias and Sulfides -- in generic terms all Sudbury metal-rich breccias and
sulfides contain some amount of iridium, cobalt & selenium. In addition, most of these same
specimens will also contain some nickel, some iron, some sperylite and some pentlandite as well
as minor amounts of several of the previously listed metals, metallic & silicate minerals. Therefore,
for example, a straw gold coloured sulfide specimen composed chiefly of pentlandite will also
contain many of the above mentioned components. As will the coppery bronze coloured
metal-rich breccias which, for example, could be described as metal-rich breccia composed
chiefly of chalcopyrite, possibly with associated cubanite, gangue inclusions, occasionally rimmed
or partly rimmed by pentlandite and also containing the iridium, cobalt, selenium, etc. in common
with many widely differing in appearance, random Sudbury metal-rich breccia and/or sulfide
samplings.
Ore -- host rock for various minerals and compounds from which various precious metals are
available in extractable quantities. By definition, in the broadest of general terms, the metal rich
breccias, sulfides and certain silicates deposited in and around the Sudbury astrobleme could all
quite easily be lumped into the type of rock known as ore. A very rich and diverse ore, but ore
nonetheless. However, when one considers the meteorite impact origin and relationship with it,
Sudbury material is far from the average run of the refinery -- "ore".
THE ENDLESS ENIGMA
Solving the puzzle ... The richly deposited widespread and diverse mineralogy of the area
encompassing the Sudbury astrobleme could be compared to or described as a geologist's dream
and nightmare all in one giant self-contained structure. The dream is being able to see such a wide
variety of rocks, minerals, and compounds, some quite rare & valuable, all occurring in close
proximity to each other. The nightmare begins when one attempts to theorize in great detail on the
impact origin of the mystery shrouded structure and how that origin effected the mineral enrichment
and deposition associated with the early crater. Each new answer seems to pose or cause a new
hypothetical question to emerge.
While it is now commonly accepted that there is a definite relationship between that extremely
ancient catastrophic impact event and the mineral-rich deposits around and below the monument
to it, no one can fully, precisely or unequivocally explain what that relationship is, or how it came
to be. At present, the complete scenario on what took place near Sudbury almost 2 billion years
ago, and how & to what degree the pre-existing landscape, geography & mineralogy were
drastically & permanently altered by the event, continues to remain a seemingly endless engima.
That fact is in part why many people find certain slices of Sudbury astrobleme meteorite impact
related specimens to be so fascinating and awe-inspiring. It evokes a sense of holding an important
piece of an enigmatic puzzle in one's hands. Certain slices seem to sum up and/or provide a
first-hand account -- eyewitness testimony, so to speak -- pertinent to the documentation of
events spanning from the moment of impact to this very day.
THE AREA'S IMPACT AND ASTEROID MINING RELATED HISTORY
Sudbury astrobleme deposits have been mined for well over one hundred years, at first by
prospectors who were later followed shortly afterward by large scale operations carried out by
international commercial corporations.
The following is a chronological history of mining & other related events, developments,
studies and breakthroughs associated with the Sudbury astrobleme:
Arrival of the Sudbury superimpactor ... 1.87 billion years ago, an earthward-bound asteroid,
moonlet or planetesimal of metal and stone composition with a total mass of approximately 35
cubic miles slams into the earth at a velocity approaching mach 100. An initial round crater, more
than 60 miles in diameter and over 8 miles deep, is instantaneously created by the Sudbury
superimpactor -- complete with numerous cracks and fractures reaching well below the shattered
crater floor, causing molten material to rise upwards into the weakened, brecciated, partially
punctured planetary crust.
Molten metal and rock of earthly and extra-terrestrial origin commence amalgamating as one while
fist to football sized fragments of pre-impact existing "stone" hurl skyward away from the ominous
gigantic crash scene, a portion of those stones clearing earth's gravitational field, becoming
deposited as meteorites of earthly origin amid other rocks of the lunar landscape and possibly on
the landscapes of other planetary bodies orbiting our sun.
How far-fetched is this probability?, one may ponder. No more or less probable or improbable
than the likelihood of extra-terrestrial debris from inside our solar system landing on this planet.
The enormous cosmic blast-induced mushroom cloud grows larger and rises higher and higher,
then slowly disperses while sorting out and redistributing target rock, molten glass & rocky
fragments, then fine dust in the form of an upper crater wall encircling the initial crater.
Finally, the crater becomes partly filled with fallout and molten material which has engulfed the
earthly remnants of the widely dispersed superimpactor that created it. The molten lake slowly
cools, primary mineral formation begins and sparks later secondary mineralization, metamorphism
and new mineral replacement processes.
1856 - nickel, an element substance first recognized by Swedish chemist Baron Alex Frederic
Constedt in 1751, that name stems from the German "kupfernickel", meaning devil's copper, was
first discovered in the Sudbury area in what at first appeared to be a small deposit by A. Murray
of the Geological Survey of Canada
1883 - a blacksmith named Tom Flannagan, while working as part of a Canadian Pacific railroad
construction crew, discovered by chance copper sulfide near the location of what became the
Murray mine, marking the historic beginning and ongoing development of Sudbury's mining
industry, as well as the following chronological chain of events:
1886 - the first Sudbury ore was produced from the Coppercliff mine by the Canadian Copper
Company
1888 - the first smelter in the area began operations at Coppercliff
1900 - the Mond Nickel Company was formed, and acquired several mines
1902 - the International Nickel Company (INCO) was created from the merger of the Canadian
Copper Company and the Orford Copper Company
1918 - completion of a nickel refinery at Port Colborne (in southern Ontario) meant that INCO
owned facilities that covered processes from mining to finished product
1928 - Falconbridge Nickel Mines Limited was established to explore the ore body at
Falconbridge, northeast of Sudbury; construction began on a new smelter
1929 - the Mond Nickel Company merged with the International Nickel Company of Canada,
partly due to shared ownership of the large Frood-Stobie Orebody
1964 - Peredery & Dietz release the results of their studies, becoming the first to provide proof to
the world of an impact origin for the Sudbury structure
1995 - Sudbury mines yielded 462,000 kg of nickel and 437,000 kg of copper on average per
day
1999 - huge platinum find -- an extremely platinids-rich zone is discovered, paralleling one side of
an offset fault near Kelly Lake
2001 - 115 years and more than 5,000 km of tunnels wide enough to drive through later, the
Sudbury deposits continue to yield their riches. Now being mined to depths exceeding 8,000 feet
with no end to the massive residual orebody in sight.
Listed here in clockwise order (all these mines circle the structure) are some of the
area's past and present mines considered as historically & mineralogically significant,
important and noteworthy:
The Whistle Capreol Nickel Rim Falconbridge Garson Frood-Stobie McKim Murray Coppercliff
The North Star Creighton Worthington Vermilion Hardy Levack Coleman Strathcona Fecunis
Lake Big Levack
Study of the Ringed Structure; Past, Present and Future -- Early in the 1990s, Robert S.
Dietz, at the time a well-known respected geologist with the USGS, authored an article on the
Sudbury astrobleme, published under the cover title "Mining an Asteroid". It makes a concise but
strong case for the feasibility and probability of a direct deposit by a large asteroid-like object
accounting for the majority of the "orebody" at Sudbury. The well-received article was a
vindication of sorts for Dietz, who at one time could be described as the Rodney Dangerfield of his
chosen profession.
After only rather preliminary study of the Sudbury superstructure early in his career in the early
1960s, Dietz was basically laughed out of the room at a geological conference for presenting his
theory and opinion on the structure by stating that the site was in fact a very large ancient impact
crater. The reaction of his admittedly more experienced peers motivated Dietz, who vowed to
prove them wrong and therefore have the last laugh in so doing.
To achieve that goal Dietz teamed up with one Walter V. Peredery, a young and upcoming
Canadian geologist who was also of the opinion that an impact origin for the Sudbury structure
was a distinct probability. The rest, as they say, is history.
Over the past 120 years, the Sudbury star wound has drawn many notable people to the site for
the purposes of researching and studying the structure and its hidden treasures. Thomas Edison
spent time there, and had his own lab, crude by today's standards, in what would best be
described as a shack located approximately half-way between Sudbury and the town of Azilda, to
the north. A.P. Coleman carried out an impressive amount of exploration, sample-gathering,
documentation, and analysis of specimens, especially considering that he did so during the early
1900s. Coleman's contemporaries included Willet G. Miller, Howe, Knight, Walker and Barlow.
Throughout the mid-1900s the area, its features and specimens were studied and reported on by
such notable names as A.R. Graham, C.E. Michener, A.J. Naldrett, E.C. Speers, J.E. Hawley
and Eugene Shoemaker. In the later era of the 1900s came Coats, Dressler, Golightly, Grieve,
Krogh, Morris, Muir, Rousell, J.S. Stevenson, Jeffery C. Wynn and Luann Becker. Last but not
least, NASA astronaut - moonwalker/geologist, "Gene" Cernan studied and collected samples of
impact material at the Sudbury astrobleme as part of his pre-moon mission, preparation and
training.
While all of these people associated with the Sudbury astrobleme have made various contributions
toward increasing our understanding of the structure and the materials contained within it, the work
of Peredery & Dietz has made the largest impact of them all -- scientifically speaking -- when it
comes down to the subject of the Sudbury basin, the ringed structure, its mineralogy and their
origin.
As an international team of equals, Peredery & Dietz were the first to locate, document, verify and
confirm the existence & presence of shattercones and the shatterconing process across a wide
area surrounding the outer perimeter of the structure. They identified many impact meltbodies &
meltsheets, shock metamorphic features and related minerals in a range of locations at the ancient
crash site. By the late 1960s, Peredery & Dietz had turned the tide of thought on the origin of not
only the Sudbury basin and surrounding structure, but the huge mineral deposit within it as well.
Both Peredery & Dietz continued to study the Sudbury astrobleme independently through the
1970s and 80s, with Dietz concentrating on deep deposits of metals, while Peredery's main field of
interest gravitated toward the study of surface meltbodies, metamorphism and the grey and black
onaping members of the structure. Peredery also worked closely with NASA scientists and
astronauts who visited, studied and gathered samples of impact related material from the site for
comparison purposes with material present and future astronauts may recover or encounter from
or around impact sites on the lunar surface.
To this day, the most thorough investigation of Sudbury astrobleme impact material is attributable
to NASA. Since only minor impact related materials study of Sudbury specimens has taken place
over the past two decades, it is apparent much more remains to be learned, not only from the
subterranean metal-rich breccias and sulfides, but from surface feature materials such as the
meltsheets, footwall breccia and the grey and black onaping fallback breccias of the Sudbury
astrobleme as well. Consider the unsolved mysteries surrounding the mineral anthraxolite as a case
in point.
Anthraxolite deposits occur at two locations in relatively close proximity within the inner portions
of the SW quadrant of the crater. It has an astonishingly high carbon content averaging over 90
percent, with some samples reportedly being composed of above ninety-seven percent fine
carbonaceous material. It is highly graphitic, higher on the hardness scale at 3-4 than anthracite at
2-2.5, has a pearly luster, is somewhat similar to Russian shungite and tends to cleave in a
somewhat cubic or hexahedral fashion. Its origin, however, remains uncertain.
If in fact the anthraxolite carbons at the 2 small Chelmsford area carbon-rich deposits were
leached out of the upper portions or outer surfaces of the nearby ejectablanket by runoff or
groundwater action before the blanket solidified and became onaping, as is most likely the case,
then surely a large percentage of the anthraxolitic carbon must be in the form of C60, C70 or
higher order fullerines of extra-terrestrial origin!
The implications of such conclusions are that, until serious scientific testing of this material takes
place to determine its higher order fullerine content levels, a potential treasure trove of richly
deposited re-solidified solar carbonaceous dust particles available right here on earth are being
completely overlooked.
While "x" amount of carbon likely derived via blast residue from the massive amount of "air" that
became spontaneously incinerated by the heat from the impact would be present as a component
of the anthraxolite, so too would be extra-terrestrial carbons in the form of bucky ball fullerines
containing extra-terrestrial helium. The important yet unanswered question pertaining to Sudbury
astrobleme anthraxolite is "what is the earthly to not-of-earthly-origin ratio of carbons in
anthraxolitic specimens of the Chelmsford deposits?" Truly a question requiring and worthy of
answering and material deserving of study by researchers interested in the field of
astro-chemistry.
Impact Melt Rock ... As is the case with certain other known impact sites, an unusual type of
material referred to as impactite, melt glass or melt rock is found at the Sudbury astrobleme. At
Sudbury this material occurs in a broad format range. As associated with only the biggest and
most catastrophic impacts on earth, large meltsheets or meltbodies exist around the Sudbury
structure. These tell-tale remnants of a time when rock became fluidal in the blink of an eye, then
cooled to become transformed into a glassy type of material, are the proverbial motherlode for
impactite specimens.
Due to the fact that this surviving material was closest of all to the ground zero target rock, it is in
the most drastically altered state. Any material closer to the impact than the meltrock was either
blown to bits, pulverized, vaporized or, along with a portion of the impacting object, possibly
transformed directly to plasma or a plasmic state. Meltrock is also found as a constituent of black
onaping, where it is contained as glassy inclusions measuring less than one inch in diameter.
The Onapings ... As alluded to earlier, the onaping breccias are quite unusual in the sense that
they are composed of small particles and fragments blasted skyward in the conical debris ejection,
that fell back to earth forming a circular deposit of fallout material released and differentiated from
the humungous post-impact mushroom cloud. As time passed, the loose dusty granular material of
which the onapings are composed became solidified, producing a very hard and unique breccia
from what was once a large, loose circle of fallout debris known as an ejecta blanket or, in
Sudbury's case, more of a circular ejecta dune or drift.
An interesting feature, peculiar to the grey & black onaping, is country rock fragments, rimmed by
fluidal glass, showing well-developed flow lines. The transition from the grey to black member
occurs over a distance of 10-70 metres (33-230 feet) although locally it can be sharp. The black
member is marked by an abrupt increase in carbon (.2-.75 percent). Muir (1983) suggested that a
zone of chloritized glass shards marks the start of the black onaping member. Abundance and size
of country rock fragments decreases from the bottom of the member to the top. The finest material
fell back from the mushroom cloud last, and was therefore deposited on top of the larger
fragments. Fragment types in the black onaping are the same as seen in the grey member, but
smaller. The black member matrix is less recrystalized than the lower grey member matrix, in all
likelihood due to the fact that it has been subjected to much less pressure than the grey member,
which has beared the weight of the black for 1.87 billion years.
Extra-Terrestrial Fullerines ... The recent discovery, by Becker et al Science Division,
NASA, Ames Research Centre, Moffett Field, Cal., of extra-terrestrial carbon containing
extra-terrestrial helium in the onaping formation at Sudbury has proven to be an important one, for
a number of reasons. First of all, it is proof that some material from the Sudbury superimpactor has
indeed survived intact to this day. Secondly, it confirms that an earlier but similar event could have
brought with it the important "ingredients" needed to create the initial conditions allowing for the
instigation of the earliest forms of life on this planet. The presence of bucky balls -- cage-like
carbon molecules containing helium atoms trapped within them -- named in tribute to Buckminster
Fuller and closely matching carbon found in Murchison and Allende carbonaceous chondrite
meteorites has caused Sudbury onaping samples to become quite an in-demand impact related
material by scientists and collectors alike.
THE PRESENT-DAY SHAPE AND CONDITION OF THE SUDBURY
ASTROBLEME
The world's largest impact structures ... The Sudbury astrobleme is the second-largest impact
site on earth, as well as one of the oldest. The Vredefort South Africa crater is the largest and, at
over 2 billion years old, is also the most ancient known crash site. Chicxulub Yucatan, the 65
million year old dinosaur slayer, measures in at third place on the world's cosmic top ten direct hit
list. The perilous Russian Popigai and Woodleigh Australia craters have the dubious distinction of
being the places where jumbo space nuggets plummeted to earth, pelting the planet and leaving
fourth and fifth ranked pock-marks, by size, as their long-lasting direct delivery cosmic calling
cards.
Throughout the long period of time since its creation, the Sudbury structure has seen the rise and
fall of many mountain ranges. One such event, the rise and subsequent weathering away of the
Grenville range south of the Sudbury structure, played a large role in deformation of the original
crater's southern wall. As the Grenville mountains were pushed upward during their birth, they
pushed the southern portion of the Sudbury ringed structure several miles north toward the center
of the original crater, accounting for its present-day odd shape.
Aerial Radar Image - Sudbury crater is the large depression middle left. Wanapitei crater is the dark lake middle right.
The Wanapitei Impactor ...
Another event responsible for drastically altering the astrobleme into
its present state was the arrival of the Wanapitei impactor which created the Wanapitei Lake
crater, approximately 36 million years ago. The name Wanapitei is derived from the Cree
language, and translates to big tooth. Strangely enough, when viewed on a map, the lake bears a
striking resemblance to a large tooth, however, that tooth-like shape is not discernable at ground
level along the lake's shoreline. The lake itself is the subject of several past and present day myths
& legends. One such belief held to this day by many locals is that part of the deep lake is
"bottomless". The lake does feature, below its surface, a rather unusual gravitational anomaly and
attracted the attention of renowned oceanographer Jacques Cousteau, who had made plans and
arrangements to conduct "in-depth" underwater research, study and exploration of the submerged
crater floor.
The much more recent Wanapitei impactor, larger than the one responsible for Arizona's meteor
crater but much smaller than the Sudbury superimpactor, slammed into the earth directly alongside
the outer portion of the Sudbury astrobleme's eastern wall, causing a large semi-circular area of
that wall to be displaced or moved westward, once again toward the central area of the Sudbury
basin. The eastern portion of the Sudbury structure and the western edge of the Wanapitei crater
actually overlap each other to some degree on the surface & at various depths. In contrast to the
deformations of the south and eastern portions of the Sudbury astrobleme, the northern and
western area of the structure remains remarkably unchanged in shape.
Shattercones ... One of a number of shock-induced features found at larger impact sites,
shattercones could be best described as shock-waves preserved or captured in stone. They are
more loosely put or termed as shock rock. Both the Sudbury and Wanapitei impacts prompted
the occurrence of shatterconing, and in the area where the structures abut, it is possible to find
shattercones associated with both impact events, in one rock face or outcrop! The only way to
determine which was caused by which impact is rather simple. The nose of the Sudbury
shattercones points toward the Sudbury structure, while the nose of the Wanapitei specimens
points in the opposite direction. Shattercones situated side by side produced by different impacts
are a rare occurrence indeed, but can be observed at Sudbury. Sudbury shattercones surround the
entire outer perimeter of the structure, range in size from a few inches to several feet and are
prized for their distinctive well-defined dominant characteristic deep grooves, converging striations
and V-shape formation.
Original size and shape of the Sudbury crater ... By following the circular outer portion of the
structure, starting at the western edge then along the northern section, and continuing that arc
outwards through Lake Wanapitei then well south of the structure, and joining back to its
beginning at the western edge, one gets a fairly accurate indication of the crater's original size and
shape before the two most significant alterations of it took place. What appears today as a large
complete crater, consistent with measurements given at the beginning of this paper, is actually the
lower central portion of what was once a wider basin with higher walls that at one time reached
much further away from the ground zero zone of the structure.
The fact that this extremely early crater is not presently perfectly round should by no means be
surprising. The amazing aspect here is that there is any visible shape to it at all. The astrobleme
actually stands out quite nicely in satellite photos, however, from the ground, due to its enormous
size, one could stand in the center of it and have no visible evidence of being inside a crater, since
the walls are too far away to distinguish the complete ring surrounding the central floor or basin of
the structure.
The world-famous, enigmatic Sudbury star wound has outlived mountain ranges, survived several
ice ages, endured tectonic forces, wind, rain and other weathering, and still proudly stands as one
of the most noteworthy cosmically created, natural wonder landmarks this planet has to offer.
To read a first-hand account of nine days of field work, sample gathering & exploring in
and around the Sudbury astrobleme, and look at specimen photos, see Sudbury Star Wound
article, Meteorite magazine, pp. 29-31, May 2000 edition.
