|Updated: Martin Horejsi’s Meteorite Books Website |
A March 1960 Witnessed Fall: Bruderheim, Canada
Timing is Everything.
A rolling landscape of fresh fusion crust blankets this 72% complete stone of Bruderheim. Falling nearly vertically onto a frozen, snow covered land, many individuals of Bruderheim retained their crust intact.
Over the past couple decades that I have been collecting meteorites, I’ve had several representatives of Bruderheim in my collection. But when the opportunity to trade for the specimen pictured above, I jumped at the chance.
According to Folinsbee, R. E. & Bayrock, L. A. in an article titled The Bruderheim Meteorite-Fall and Recovery published in the Journal of the Royal Astronomical Society of Canada, Vol. 55, a wonderful slice of recent meteorite history is chronicled. This months installment will feature excerpts from the article with author commentary within the captions of the photographs and graphics.
Bruderheim, a gray chondritic meteorite which fell on March 4, 1960, at 1 :06 a.m. Mountain Standard Time, is, in aggregate weight (over 300 kilograms), Canada’s largest known meteorite (Millman 1953). By strange coincidence the bolide detonated halfway between the point where the Edmonton meteorite was found, and the Abee meteorite fell.
At 1 :06 in the morning the late show on television had just finished, a factor adding substantially to the number of eye witness accounts. Bruderheim is a typical evening meteorite, solving the entry problem’ by reason of its relatively low atmospheric velocity.
If this were a piece of pottery entered in an art contest, it would no doubt lose. And with good reason. But since it is a meteorite sculpted by atmospheric forces, it is truly a work of art.
The pockets of superheated surface captured perfectly the events taking place on this meteorite’s surface as it fell. Given that many reports claim that freshly fallen meteorites were warm or even too hot to touch immediately after they fell, I would have hoped that studious observers of such things would have provided commentary about the immediate physical situation in which the found stone was nested.
photo courtesy of: http://www.meteoritecollector.org/
Earl Milton, past president of the Edmonton Centre of the Royal Astronomical Society of Canada, was instrumental in alerting the public through the media of press, radio and television, to the possibility that a meteorite fell from the bright detonating bolide.
He obtained eye witness reports that narrowed down the possible fall area. Stanley Walker and Tyrone Balacko of Fort Saskatchewan, following a lead given by recovery of a single fragment, mapped the principal fall area in outline, and recovered about 75 kilograms of meteorite in the two days immediately after the fall. Heavy snow then fell, and no further recoveries were made till spring.
|This old photo shows the range of sizes of Bruderheim individuals. Two individuals were more than 30kg with another four between 20-30kg , and another four between 10 and 20 kg. Additionally another 500 individuals smaller than 100g each were collected.|
The Bruderheim bolide was probably first observed by Alexis Simon, an Indian of the Paul’s Band Indian Reserve at Duffield, Alberta. His account is as follows: On the night [sic] of Friday, March 4th, 1960, I happened to be outside of my home at midnight when I saw a large meteorite in the north-westerly direction from Duffield. It lighted up the sky as it passed swiftly in a north-easterly direction, giving off what appeared to be flashes of fire.
He describes also a rushing sound, resembling a high wind, which lasted for 5 to 6 seconds after the fireball passed, a phenomenon distinct from the shock-wave detonations accompanying meteorites, and characteristic of reports of fireballs (Smith and Hey 1952). It may be primarily due to suggestion, without real existence (Heard 1949).
One of the larger individuals of Bruderheim was measured, then broken to pieces. As demonstrated in the picture above, examination could be painful.
I suspect that if one staged a similar photo today, it would be treated as either a joke or meteoritical blasphemy.
It is interesting to speculate that the more acute senses of Alexis Simon enabled him to observe the meteorite during the time when it first was entering the atmosphere, and to note a sound phenomenon not recorded by other observers whose vision and hearing, dimmed and dulled by television, were quickened only by the bright glare of the fireball lower in the atmosphere, and shaken by the sonic boom at detonation point. However, more prosaically, there was considerable patchy overcast in the Edmonton area, and at Newbrook, though the all-sky camera was on and recorded the general brightening brought about by the bolide at 1:06 a.m., the meteor cameras were not operating (Jack Grant, Newbrook, personal communication).
Mrs. P. I. B. Wood of Carvel observed the fireball from point of detonation to disappearance, as did a number of observers from the slightly overcast city of Edmonton. The most accurate observations of which the writers have record were made from Edmonton by D. B. Russell, a student at the University of Alberta, and from Beverly by M. Reis at the Texaco Oil Refinery. Cross sighting was made by S. E. J. Mitchell of Clyde and by a number of observers near Egremont and in Fort Saskatchewan (Miller 1960).
This strewnfield map show the distribution of Bruderheim individuals.
Connecting the dots, I’d guess that a couple of stones of size landed in the river. Further, looking at the density of specimens across this large expanse of land, I would not be surprised if more modern methods of searching were employed, many more, albeit weathered, specimens would be found.
Hey Meteorite Men! You guys listening?
Some of the sighting and sound data from the Egremont district suggested a fall area north-east of this village: flash sound intervals were small, averaging 20 seconds (from seven observations where time could be judged by repeating motions). L. A. Bayrock and R. S. Taylor spent considerable time in air and ground searches in this area on March 6th and 8th, and as late as April 4th, with negative results. The theory that the Bruderheim bolide had an initial north-easterly trajectory, and at the detonation point split into two main masses, one traveling approximately north 200 east over Egremont, the other 1000 (100 south of east) to fall in the Bruderheim area, while plausible, has not been substantiated by finds.
The assignment of an azimuth of north 1000 to Bruderheim is based largely on the shape of the ellipse of fall and on the fact that most of the sighting evidence does not directly contradict such an interpretation. One hundred miles east of the fall area, on this 1000 azimuth, Mr. and Mrs. A. C. Butz of Dewberry observed the flash and ” … about two to three minutes after light, a thundering noise was heard, windows rattled….” This is the outer limit of sound reports.
|A wall of L6 matrix dominates one side of my specimen. Although a few larger chondrules are poking out of the gray monotony, and some mild specks of rust coloring add hints of life to wall, it’s just a fact of life that the interior of L6 chondrites are often the least exciting visuals of the meteorite world.|
Though it is clear that the bolide first became brightly illuminated almost directly north of Edmonton, reports of its height at this time vary greatly, and the slope of the path and the geocentric velocity needed for calculation of the radiant, or direction in space from which the body was coming, are not easily judged. The best evidence suggests that at a height of about 30 miles the fireball flared a bright blue-white, of sufficient intensity to attract the attention of ground observers, and continued in this halo of plasma-type illumination for 25 air miles to the detonation point at a height of 16-17 miles.
Fragments thrown off at detonation remained bright, though changing from white to red as they approached the ground point, about 25 air miles east of the point of detonation. The slope of the illuminated path therefore was about 40°, and since most observers recorded a 5-6 second duration for illumination, the geocentric velocity was about 8-10 miles per second. This interpretation is a best fit interpretation of available sighting data. Heard (1949) describes a fireball similar in many respects to Bruderhein1, and gives the equations necessary for solution of the meteor’s path in space, given azimuth, slope, and geocentric velocity. I t becomes clear, on examining the university report forms (based on a Russian example), that these were too complex for an unskilled observer. Most of the forms that were turned in provided little more enlightenment than this initial letter received from John Mandryk of Bruderheim: “I have seen the light and heard the crash. If you wish to send me a form I shall answer it to best of my ability.”
Tyrone Balacko and Stan Walker posing with some of the Bruderheim meteorites they recovered. The pair found about 75kg of meteorites within two days. After than, the snows fell and the search efforts were put on hold until spring.
Again, note the geologic hammer.
photo courtesy of: http://www.meteoritecollector.org/
Matt Krys holding a Bruderheim meteorite. A majority of Bruderheim specimens in the University of Alberta’s collection were purchased from farmers. It became clear early on that the locals of the area were more adroit at finding the cosmic stones than those visiting the area just to search.
photo courtesy of: http://www.meteoritecollector.org/
Nick Broda, a farmer of the Bruderheim district, recovered the first stone from his barnyard on Friday, March 4. It was brought to the Sherritt Gordon Nickel Refinery at Fort Saskatchewan by an employee, and identified as a meteorite. S. Walker and T. Balacko proceeded to the area and began systematically to map the fall and recover fragments which, upon striking frozen ground, had rebounded onto the hard-packed snow surface where they became clearly visible from district roads. On Saturday and Sunday, March 5 and 6, Walker and Balacko mapped and collected a total of 155 pounds of meteorite, which they later made available to the university as the nucleus of its collection.
At the same time district farmers collected fragment B-74, a complete individual weighing more than 25 kilograms. This stone was then broken by the collectors into a number of fragments, and widely distributed. Most of these pieces mere ultimately acquired by the university, and since B-74 was a completely unweathered specimen it was used as the source of all samples employed in analyses of the meteorite. Andreas Bawel and Walter and Nick Holowaty of Bruderheim collected about 10 kilograms of fragments from their farms on March 4, 5, and 6. Walter Holowaty made the first collections off the ice on the North Saskatchewan River, digging down through the snow to the ice surface wherever he observed an impact hole. On March 7 it snowed heavily and no further recoveries could be made until spring, with the exception of a few small fragments collected from snow banks.
|Another side of my specimen contains an almost unbroken wall of crust. Having a fist-sized chunk of crusted meteorites is always a treat to be savored. Luckily, the curators who managed this rock for the decades prior to my ownership were careful stewards preserving the integrity of this beauty.|
Bruderheim individuals struck the ground almost vertically, apparently at terminal velocity, perhaps 200 miles per hour at impact. The largest fragments, weighing 30 kilograms, traveled farthest, and are grouped at the south-east apex of the ellipse. They dug holes about 8 inches deep in the frozen ground and then rebounded onto the snow surface, ending up about 6 to 8 feet east of the impact point, with a shower of dirt splayed south-east of the impact craters. One individual fell onto a cushion of swathed wheat. The position of these large individuals confirms the 1000 azimuth traced by the fireball, coincident with the axis of the ellipse of fall.
Point of impact of the larger fragments (greater than 4 kilograms) was surveyed with a plane table. Smaller individuals were plotted from the Walker-Balacko map, from mapping on aerial photos while collecting, and from all reliable information obtained from farmers in the area. The Bruderheim bolide continued breaking up into smaller fragments even after the initial detonation at high altitude, and in this and other respects the fall resembles Tenham (Spencer 1937). A small but significant number of fragments, perhaps 10 per cent. of the individuals, show partial fusion crusts, in one instance three stages, late-formed fragmentation surfaces that are not completely blackened. There is evidence from the fall pattern that some individuals broke into two or more pieces while still in the air, though traveling below the speed at which fusion crust would form. In the case of the smaller individuals, direction of fragments from pits is almost random, though there is a suggestion of it being outward from the centre of the ellipse. This probably represents motion imparted by the detonations. These smaller individuals in some cases rebounded onto the snow surface
Icing on a cosmic cake. The University of Alberta designated Bruderheim as locality number 4270 in their collection. There is an online catalog of specimens including some great pictures on their website. http://www.museums.ualberta.ca/dig/search/meteors/results.php?typ=2&advmet=bruderheim
The specimen label painted on my specimen indicates that it is number 8 in the U of A’s Bruderheim collection, and originally weighed 706 grams. When you click on the link to the collection pieces, check out all the fine pictures including the small complete oriented individual of Tagish Lake.
Most of the material recovered from Bruderheim was in the form of individuals weighing over 4 kilograms. There is a significant grouping of weights around 25-30 kilograms, which seems to be an optimum size for chondrite fragments surviving the penetration of the earth’s atmosphere (Lightfoot, MacGregor and Golding 1935), as evidenced by the weight distribution of stones in the British Museum.
In this tearsheet of meteorite history, a newspaper clipping revisits the Bruderheim meteorite fall. I especially enjoy the final line:
“Scientists were elated because of information it revealed about the nature of radiation in space, the origin and nature of the solar system and indeed the universe.”
Wow. Not a bad scientific haul from one ordinary L6. The universe? Really?
As Until next time….
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