|Prologue: Geology and Natural History||Geology, ecology, bibliography|
|Precambrian (Grenville) Shield||Basement rocks|
|--- Gabbro Erratic||Large boulder in Campbellford|
|Ordovician Limestones||Limestone platform|
|--- Outcrop by the Trent||"Ranney Span" suspension bridge|
|--- Local Fossil||Bryozoan in limestone|
|In (geologically) Modern Times|
|Quaternary, Surficial Deposits||The Ice Age and glacial retreat|
|News, e.g., Fireball Events||No meteorites, yet!|
|Crowe Bridge Conservation Area||Natural History slide show|
|Algonquin Park History||Guest Pages by Mary Garland|
|Weather, News, other Local Links||Weather, tourist attractions|
|Local Natural History|
|Birds||Township bird list|
|Ecology||Local plants, trees, animals|
|References||Local geological bibliography|
|Snow summary, Nov. 2007 on (189 kb)||See also snowfall in Ecology pages|
|Ferris Park: Natural History Walk (68 kb)||Early October (2pp.)|
|Ferris Park: Geology (185 kb)||Illustrated (2pp.)|
Since 1998 Turnstone's office has been located in Campbellford, a town on the banks of the Trent river in eastern Northumberland county. This area of southern Ontario is dominated by rolling farmland and woodland, near the centre of a triangular region defined by Toronto, Ottawa and Kingston. Three distinct periods of geological time are beautifully displayed within the area. The Precambrian rocks of the Grenville province of the Canadian shield are exposed at intervals along Highway 7, within 20 km to the north of Campbellford. The immediate bedrock of the town is Ordovician limestones. A veneer of surficial deposits was brought, sculpted and left behind by glacier ice and associated drainage channels in the geologically recent past, in the Quaternary period. This economically-vital "skin" on the bedrock tops this grand layer-cake of history and provides many of the most accessible landscape features.
An illustrated summary of the natural history of the region is slowly evolving on this site. A township bird list of more than 120 species is now available, and serves as an index to selected local birds, beginning with an impressive, regular summer visitor, the osprey. In addition, 360 or more of the more-common wild flowers, trees, and animals of the area can be found in a listing of the local flora and fauna. To see an example of the fossils found in the limestones, click here. A compact bibliography of the geology and history of Campbellford and district is also available. N.B. This section, like certain other parts of the web site, varies in the technicality of its presentation. A choice may eventually be offered, as in the sections on the geology of Lake Superior.
Introduction to Local Geology
1. The Grenville province of the Canadian shield represents the middle Proterozoic eon of Precambrian time, rocks formed relatively deep in the Earth's crust roughly 1200 million years ago. The Grenville forms the southeast marginal belt of the much larger Canadian Shield. It disappears from view in southwest Ontario, buried by a younger sedimentary platform to the south of a line that strikes west from the Kingston area past Tweed, Marmora, the northern Carden Plain and the north end of Lake Couchiching at Washago, into Georgian Bay north of Midland. However, it is part of a much larger geological province that is found from Scandinavia to South America, a large part of it forming the bedrock from Newfoundland through much of southern Quebec, southeast Ontario, and the Adirondack Mountains of upstate New York.
The geology of the Grenville province is complex and well- documented: I know of some 3,000 articles, books and reports on the region. The Grenville is more properly an orogen, the remnants of an ancient, Himalayan-scale mountain range and adjacent lands and seas: think of a modern-day traverse from the Arabian Sea across the plains of Pakistan to the high peaks of the Karakoram! The geology and aspects of the mineral deposits of the Ontario sector of the Grenville province are reviewed by Easton (1992) and Easton and Fyon (1992).
The ages of crystallization and recrystallization of these rocks can be estimated in a number of ways by the products of radioactive decay in suitable minerals. Thus the proportions of isotopes of lead in grains of the mineral zircon, formed in part by decay of isotopes of thorium and uranium, can yield precise estimates of the crystallization of magmas and episodes of heating and deformation in the crust. The shield rocks predominate north of Highway 7, which runs through or near such towns as Norwood, Havelock, Marmora and Madoc.
There are minor inliers of Grenville basement in northern Seymour township, within younger (Ordovician) cover rocks of the Gull River and overlying Bobcaygeon formations (see Section 2). Two such instances lie along the Crowe River drainage, just south of Crowe Bridge and around the bridge at Allan Mills (Carson, 1980). Bobcaygeon Formation rocks form the immediate bedrock from downtown Campbellford north to the confluence of the Trent and Crowe, while younger Verulam Formation limestones appear downstream, from Ferris park and Ranney Falls to the south. Thus the Precambrian rocks of the Canadian Shield appear at surface as close as 8.5 km N.N.E. of Bridge Street in Campbellford. They predominate north of a line through Tweed, Madoc, Deloro, Marmora and Round Lake, although small outliers of bedded limestone survive above the basement: a good example is found on a hill crest on the Havelock- Apsley road near Nephton.
The gabbro erratic on Grand Road
Many pebbles and larger blocks of Grenville rocks were carried down by the Laurentian ice sheets. A plaque was erected beside Grand Road in Campbellford, on 01 November 2002, celebrating a large and attractive example of erratic boulder in the IODE Parkette, composed of a striking rock type known as gabbro.The local geology in the Belmont-Cordova region to the immediate north of Campbellford is described by Bartlett and Moore (1981), Davis and Bartlett (1988), and Davies and Whitehead (2001). The Cordova gabbro itself, and numerous other such intrusions in the Grenville, are described briefly by Wilson (1994).
Geology and Minerals of the Grenville Province
The Grenville sector of the shield has a long and complex geological history. It contains a wide diversity of mineral deposits that were exploited, generally by small surface and shallow underground mines, in the 19th and early 20th centuries. Commodities include gold, lead, zinc, iron, molybdenum, uranium, and "industrial minerals" such as apatite (phosphate), feldspar, micas, graphite and wollastonite. Some operations continue to this day, across a wide region from Georgian Bay in the west to the Ottawa river in the east, and thence far to the east through southern Quebec to Labrador. Modern Ontario operations include mining and quarrying for talc, calcite, dolomite, building stones such as granite, and ornamental and semiprecious stones such as sodalite. Intermittent exploration continues to this day, for a range of targetted commodities such as base and precious metals and graphite.
Bartlett,JR and Moore,JM (1981) Marmora, Belmont and southern Methuen townships, Peterborough and Hastings counties. OGS Misc.Pap. 100, 73-76.
Carson,DM (1980) Paleozoic geology of the Bannockburn- Campbellford area. OGS map P2374, 1:50,000 scale.
Davies,JF and Whitehead,RE (2001) CO2, alkalies and REE systematics in hydrothermally altered gabbro hosting the Cordova gold-bearing veins, Ontario. Explor.Min.Geol. 10, 321-328.
Davis,DW and Bartlett,JR (1988) Geochronology of the Belmont Lake metavolcanic complex and implications for crustal development in the central metasedimentary belt, Grenville Province, Ontario. Can.J.Earth Sci. 25, 1751-1759.
Easton,RM (1992) The Grenville province and the Proterozoic history of central and southern Ontario. In `Geology of Ontario' (Thurston,PC, Williams,HR, Sutcliffe,RH and Stott,GM editors), OGS Spec.Vol. 4, part 2, 715-904.
Easton,RM and Fyon,JA (1992) Metallogeny of the Grenville province. In `Geology of Ontario' (Thurston,PC, Williams,HR, Sutcliffe,RH and Stott,GM editors), OGS Spec.Vol. 4, part 2, 1217-1252.
Wilson,GC (1994) Mafic-Ultramafic Intrusions, Base-Metal Sulphides, and Platinum Group Element Potential of the Grenville Province in Southeastern Ontario. OGS OFR 5880, 196pp.
2. The Ordovician limestones which lie unconformably upon the Grenville basement are often exposed in low, almost flat-lying outcrops along highways and river banks. Most bedrock outcrops in the region occur either along the unconformity between the Grenville basement and Paleozoic cover rocks, or along the major rivers such as the Trent (Carson, 1979). The Paleozoic strata are generally flat-lying, except where draped over irregularities in the Precambrian basement. The Paleozoic strata of Ontario are described by Johnson et al., 1992. The fossils of our region of south-central to southeast Ontario are documented by Hessin (2009) in an excellent self-published monograph with fine photographs of beautifully prepared fossils.
So-called "pop-up structures" are seen in three locations: northwest of Young's Point in the Gull River Formation, at King's Mill (Wellman) in the Bobcaygeon Formation, and near Woodview in the Gull River Formation. These are referred to as neotectonic features, meaning that they are of geologically recent (Quaternary) origin, presumed to reflect the relaxation and flexing of rock layers relieved, roughly 11,000 years ago, of the weight of the mighty Laurentian ice sheet.
The middle Ordovician is divided into five formations: the Basal Group is the shale, sandstone and arkose of the Shadow Lake Formation. The overlying Simcoe Group is divided into the Gull River Formation and Bobcaygeon Formation limestones, the Verulam Formation (limestone and shale) and the Lindsay Formation (limestone).
This summary is derived from Carson (1979). The limestones have been explored in the past for lithographic stone, while modern quarrying extracts large tonnages for the chemical and metallurgical industries and for building and ornamental stones.
A casual reconnaissance of the limestones of the Gull River, Bobcaygeon and Verulam Formations of the Simcoe Group in the Campbellford area was initiated in 1998. Results to date suggest that brachiopods and bryozoans are the most widespread bioclasts, with lesser crinoid and rare trilobite fragments. Algal oncoliths are locally abundant. Accessory minerals include quartz and chalcedony, pyrite and goethite, and brown phosphatic collophane. Silica and pyrite are found in the lower formations, collophane in the younger Verulam Formation, and traces of iron oxyhydroxides are present throughout. In terms of a limited suite of field observations and reference samples, the micrite content (fine-grained facies of the limestone) falls from roughly 70 to 30 volume percent from Gull River to Verulam strata, and the bioclast proportion rises from 15 to 50 percent.
Suspension Bridge at Ranney Falls
The following illustrations of the local Verulam limestone depict a bluff of horizontal strata on the west bank of the gorge of the Trent river, near the south end of "Trent Island" and on the immediate south side of the outfall of the local hydroelectric power station. The bluff was selected as the site of the western end of what is now a fine pedestrian suspension bridge below Ranney Falls, linking Trent Island and Locks 11-12 of the Trent waterway with Ferris Provincial Park, on the east bank. The complex concrete-and-rebar foundations of the bridge were emplaced by the end of November 2002, and the span of the bridge was erected by contractors, including engineering specialists of the Canadian Armed Forces based at nearby Trenton, in the second half of the following year. The bridge was completed in the first half of December, 2003. Landscaping work at either end of the bridge preceded a well-attended official opening on 23 June 2004.
This addition to the local hiking trails will be significant, as the former railway grades are added to the nationwide system of the Trans-Canada Trail. The Trail and related links are now open eastwards from Campbellford to Stirling, Tweed and points east. Recent initiatives may soon open the westward section of the old rail line to Hastings: during November 2004 a local snowmobile club, the Percy Boom River Rats, was busy installing a bridge over a creek as part of a program of reconstruction along the line. A simple explanation of the bridge site follows, below the photographs.
The view on the left shows the top of the 12-metre-high bluff, looking north over Ranney Falls towards the town of Campbellford, represented by its water tower. Ferris park lies on the east bank (on the right in this image). At the centre is a small perched block of the limestone cap, ready to fall into the river below. This view is looking southeast from the site in the first photo, a few metres distant. The block is roughly 1 metre thick. On the right is a winter view of the gorge --- again with Laddie the dog for scale --- the area is an attractive outdoor destination year-round!
This overlook provides a view of the Trent river at one of the more active sections of its course. The river's bed and sides, including the bluff on which you stand, are composed of horizontal layers of rock of middle Ordovician age. These beds are limestones with lesser layers of shale. The limestone contains fossils such as corals, bryozoans, crinoids and brachiopod shells. Known in southeast Ontario as the Verulam Formation, the limy sediments are believed to have been deposited in a warm, shallow sea roughly 460 million years ago.
The hilly terrain of Ferris Provincial Park, on the east bank of the river, was sculpted by the forces of the Laurentian ice sheet which retreated from this region some 12,000 years ago. The ice left its signature on the landscape, depositing silt, sand and boulders in the forms of whaleback hills (drumlins) and sinuous ridges (eskers).
Over here, within 10 metres of this spot, a careful hunt may reveal small pieces of bubbly slag and dense firebrick. One explanation is that these represent boilers associated with a tannery which operated on this bank, just upstream to the north.
The Suspension Bridge
The bridge was officially opened on 23 June 2004. The gentle arc of the metal walkway is some 93 metres (300 feet) long. At low water in the summer months, the centre of the walkway is at least 11 metres (36 feet) above the water level.
The Limestones and their Fossils.
Three samples from the perched block, shown above, were taken for microscopic analysis. One of the samples from near the prow of the rubbly outcrop on the right is a brownish-grey bioclastic limestone with decreasing amounts of brachiopod, bryozoan and crinoid fossil trash. It represents a part of the Verulam Formation of the Simcoe Group, at the top of the middle Ordovician (Llandeilo age, circa 460 Ma). The rock contains decreasing proportions of sparry calcite, bioclasts, and fine carbonate (micrite), plus traces of detrital quartz and phosphate (collophane) replacing a small fraction of the shell material. A section through a bryozoan colony displays alternating structures, representing arrays of individual organisms in the colony, known as autopores (0.25-0.30 mm in diameter) and smaller mesopores (0.04-0.08 mm wide). The bryozoan is thought to be a species of the genus Prasopora. Brachiopods in the outcrop may include representatives of genera such as Strophomena and Rafinesquina.
Here is a photomicrograph of a colonial bryozoan in a sample of limestone from the bluff, showing the individual organisms that comprise the colony.
Sample 2359, bioclastic limestone. 40X magnification, long-axis field-of-view 2.8 mm, in plane-polarized transmitted light.
Carson,DM (1979) Paleozoic geology of the Peterborough- Campbellford area, southern Ontario. OGS Misc.Pap. 90, 146-148.
Hessin,WA (2009) South-Central Ontario Fossils: a guide to the ancient marine life of the region. W.A. Hessin, 9214 Danforth Road East, Cobourg, ON K9A 4J8 (firstname.lastname@example.org), 286pp. plus CD-ROM.
Johnson,MD, Armstrong,DK, Sanford,BV, Telford,PG and Rutka,MA (1992) Paleozoic and Mesozoic geology of Ontario. In `Geology of Ontario' (Thurston,PC, Williams,HR, Sutcliffe,RH and Stott,GM editors), OGS Spec.Vol. 4, part 2, 907-1008.
3. Quaternary Geology is an Earth-science discipline which covers the past two million years of Earth history. Although this a short span in the development of our planet, roughly one twentieth of one percent of the estimated age of the Earth, the Quaternary is important to us in many ways. In higher latitudes, this period saw the waxing and waning of massive ice sheets which, at their full extent, stretched as much as halfway from the poles to the equator, and sculpted the landscape in many ways. The Quaternary incorporates both the past 10,000 years or so, the Holocene period, which includes all of recorded human history, and the much longer Pleistocene period which preceded it. Quaternary processes provide critical controls on water resources, and on the distribution of some of the "industrial minerals" necessary to modern civilization, such as sand and gravel deposits.
Glacial landforms that exert a strong influence on Trent Hills include the tallest features, known as drumlins and eskers. Drumlins are whale-backed hills, as seen in northern Ferris park, while eskers are sinuous ridges, a good example of which lies on the west side of Campbellford. The orientation of these features offers a general indication of the down-slope direction of the ice at the time, though in an ideal world the geologist seeks striations in bedrock (scratches made by stones embedded in the base of an ice sheet or glacier as it moves).
News Flashes & Archive of Local News
04 May 2014: On a cool, breezy, cloudy-bright Sunday afternoon at about 16:16 hours local time (UTC-5) a daylight fireball event occurred across southern Ontario. In addition to the bright fireball, loud sounds and shaking of buildings were reported, consistent with a potential meteorite-dropping event. Some video information exists, but the local fireball camera network does not operate in daylight hours, so initially no precise fall zone could be predicted. Seismics, infrasound and weather radar can all provide further clues. Numerous witnesses to the visual and/or sonic phenomena provided information. The fall phenomena were seen and heard in Toronto and points east, along and north of Highway 401, with numerous observers in the Peterborough-Lakefield area. The dust cloud recorded in some images, in the aftermath of the fireball, suggests that much of the body disintegrated high in the atmosphere, and it is currently unclear whether anything survived to reach the ground. From my own conversations with people in the week following the event, I understand that the fireball and/or associated sounds were noted in a roughly west to east belt from Simcoe and Brampton across the Greater Toronto region to the north side of Peterborough, Smith township, and across the Campbellford-Stirling area (e.g., Campbellford, Codrington, Pethericks Corners and Stirling) to Cordova Mines in the north and Belleville to the south. Observers 6 km west of Campbellford described an ongoing rumbling sound, lasting for approximately ten seconds. This lengthy soundtrack was affirmed by another observer in Trent River, north of the town.
Early analysis from Prof. Peter Brown at Western University places a possible fall in eastern Northumberland county or western Quinte West (aka southwestern Hastings county - why must politicians constantly fiddle with place names?!). The best-guess from incomplete data appears to be an E.N.E.-trending belt from south of Warkworth to south of Stirling.
Four weeks after the event, I have not heard any credible report of a meteorite find, having conducted nine searches and field visits to four separate areas along the fireball trajectory between May 5th and May 29th (west and east from Codrington, the Murray Marsh, and areas near Glen Ross and Stirling). A team of seven searched some 8.5 hectares (21 acres) of two fields on Sunday 11th, a useful exercise in perfect weather, but did not recover any meteorites. Approximately 50 information packages were distributed to landowners and interested parties, direct or via rural mailboxes. There is a chance that one or more meteorites will be recovered - perhaps before any meteorite from the 12 December 2011 Selwyn / Stony Lake fireball event (qv).
Barring a chance discovery of meteorites on the ground, this event will probably join the majority of such sightings, that do not result in a meteorite recovery. The major problem with better constraining the possible fall area from the fireball was a lack of eye witnesses near the eastern end of the track (from Cobourg to Belleville, say, and points north past Norwood and Madoc) whose testimony would have been especially valuable.
Last updated: Monday 09 June 2014, 22:00 hrs.
Deeth,S (2014) Loud, speeding fireball the size of a beach ball. Peterborough Examiner, A1-2 (06 May). Versions were also published in the Belleville Intelligencer and Community Press.
15 February 2013: infall of extraterrestrial material, and potentially a large meteorite shower in the Ural region of south-central Russia, followed a deafening fireball event over the area of Chelyabinsk, south of Yekaterinburg. These events result from the entry into the Earth's atmosphere of a small body, often of asteroidal material, referred to as a meteoroid during its passage, and as a meteorite should it survive to reach the ground, and not burn up in the atmosphere. Common meteors or shooting stars are dust-size material entering Earth's atmosphere. An exceptionally bright meteor is known as a fireball or bolide and may involve material (a meteoroid) large enough and tough enough that fragments reach the Earth as meteorites. Although meteorites often arrive as a single individual, or as many as tens of fragments, on occasion a meteorite shower may deposit as many as thousands of individuals spread out over a broad strewnfield.
Numerous spectacular video recordings were made of the event, at 09:20 hours local time (UTC+6, or 11 time zones ahead of EST).
A meteorite fall into a frozen lake, and a 6-metre-wide crater on the lake shore, were initially reported 1 km from the town of Chebarkul (circa 60°22'E, 54°59'N), some 70 kilometres W.S.W. of Chelyabinsk. The media emphasis on images of a circular hole in lake ice showed no crater. Possibly the broken ice and reported crater were one and the same phenomenon. The area lies in Chelyabinsk Oblast, east of the tortuous border with Bashkortostan, north of the international border with Kazakhstan. There are numerous lakes within 5 km in an arc from northeast to northwest to southwest of Chebarkul.
The initial videos suggest to me, a non-expert in such matters, some fragmentation of the fireball, consistent with a stony meteorite of some kind. It is worth noting that the extensive damage, and injury to some 1,200 people, were due to the indirect effects of the blast wave and sonic boom as the fragmenting body entered the lower atmosphere. The loud blast caused failures of human structures, particularly breakage of window glass, which was epic in scale. It was soon estimated that some 200,000 m2 of window glass was damaged or destroyed in 4,000 buildings. The reported damage (other than the lakeside impact, perhaps) were not due to direct strikes by falling meteorites. No dangerous radioactivity is associated with such events, so no further danger is anticipated, except perhaps from collapse of weakened structures, such as roofs, walls and windows.
Many facts remain to be verified. It is worth bearing in mind that there are no indisputable cases of human fatalities due to direct meteorite strikes (unlike far-more-common lightning strikes, though even with lightning some 90% of victims apparently suffer non-fatal injuries). There are some suggestive ancient records, but these relate to events far away in time and space, and the cause of death is impossible to verify. A number of people have been struck, bruised and frightened by meteorite falls during the 20th century, and numerous cases are on record of buildings or vehicles being struck. The falling bodies are typically quite small, denting vehicles, cracking windshields, or making small holes in roofing materials.
To what else can we compare this event in recent history? Two 20th-century events immediately come to mind, provided that meteorites are recovered, as seemed inevitable from the earliest reports.
1) In 1947, the fall of the Sikhote-Alin IIB iron meteorite in Siberia generated 106 documented impact holes on the ground. At least 23 tonnes or iron meteorite were recovered, mostly as rather jagged, shrapnel-like fragments (not really the norm for iron meteorites, though other examples are Whitecourt [Alberta, Canada] and Gebel Kamil [Egypt]).
2) On 08 March 1976, the largest-known stony meteorite in modern times slammed into northeastern China. The Jilin (Kirin) meteorite shower yielded some 4 tonnes of stony meteorite. One mass, at 1770 kg, is the largest single stony meteorite mass recovered so far. Numerous small craters were made by the fall of individual fragments into frozen soil, the largest mass penetrating several metres into the ground. Fragments were recovered over a strewnfield of about 500 km2. Jilin is classified as an H5 ordinary chondrite, one of the most commonly-recovered types of meteorite.
It seems ironic that the area is home to a human-made disaster of epic proportions, much less-known than the Chernobyl nuclear power-plant disaster in Ukraine, in 1986. On 29 September 1957, a waste dump associated with the Mayak military reactor complex, making plutonium for nuclear weapons, is thought to have undergone a conventional explosion of chemicals in the dump. The Mayak event, 100 km northwest of Chelyabinsk, spilled a vast amount of radioactivity into the environment and down the Techa river. The blast and dire consequences were shrouded in secrecy at the height of the cold war.
Stranger still, the meteorite collision with the Earth over Russia occurred at about 22:20 hours EST on 14 February, just 16 hours before the predicted passage of a small asteroid close to our planet. Asteroid 2012 DA14 was expected to pass Earth at a distance of 27,600 km, with its closest approach at 14:25 hours EST. This NEO (near-Earth object) is an asteroidal fragment, like most meteorites, and much larger than the object that crashed into Russia. 2012 DA14 has an estimated diameter of about 45 metres and a mass of 130,000 tonnes. The NEO and the Russian bolide are thought to be unrelated, a remarkable cosmic coincidence.
In due course we'll take another look at this fireball and evident meteorite shower, update and as necessary correct these initial data (first posted about 14 hours after the event), and see how it compares with historic meteorite falls. It seems that we can expect at least 2 or 3 such dramatic air blasts, with or without multi-tonne meteorite falls, within a human lifetime. The likelihood of being hurt by such an occurrence are incredibly small, although the chances that some unlucky people may be hurt have risen with the skyrocketing global population in the past century.
Posted by Graham Wilson, 12:45 hours EST, Friday 15 February 2013. For further information on meteorites at this site, please go to the site meteorite index.
POSTSCRIPT: preliminary analyses from labs in Russia, the U.S.A. (NASA) and Canada (Meteor Physics Lab, Western University, London, Ontario) indicate that the total energy release in the event was approximately 470 kilotons of TNT-equivalent, roughly 22 times that of the Nagasaki A-bomb, or 31 times the Hiroshima bomb (best estimates for those being 21 kT (±10%) for Nagasaki, 15 kT (±20%) for Hiroshima). This would be the largest recorded atmospheric infall of an extraterrestrial body (however classified: meteorite, asteroid, comet) since the great Tunguska event in Siberia, back in 1908. Fortunately, most of this vast energy was expended in the atmosphere (in displacing, heating and ionizing gas molecules; and in heating, breaking and vapourizing most of the incoming projectile). This must be another indication that this, like the majority of meteorites, was a stony body (or maybe an icy cometary remnant): a more coherent mass of a substantial iron impactor, such as the Sikhote-Alin fall of 1947, could have survived to transmit kinetic energy to impact on the ground.
The initial analysis from the group headed by Prof. Peter Brown at Western University matches the wealth of available data (global infrasound measurements in particular) with arrival of a 15-metre-wide, 7,000-tonne meteoroid, travelling at a velocity of 18 kilometres per second.
The initial efforts of divers in Chebarkul Lake were unsuccessful, due in part to a thick layer of ooze on the lake bed. Reports of meteorite falls into lakes go back decades, and recovery efforts are seldom if ever successful. However, on an event of this scale one would expect additional material to be found on land, and with snow on the ground this could happen soon. The early-stage report that the body originated in the asteroid belt is encouraging for meteorite hunters. However, depending on the nature of the fallen material and the resources employed, we may have to wait for spring for many more answers.
Posted at 12:15 hours EST, 16 February 2013 and last updated at impact+60 hours, 11:20 EST, Sunday 17 February 2013.
LATEST: as of 18 April 2013, little more had reached my ears concerning the impactor, said to be an ordinary chondrite meteorite. The most impressive result to date concerns the speed and reliability of the initial analysis, by Peter Brown et al. at Western. The estimates quoted above, made within 24 hours of the news of the event, have apparently changed little in two months of subsequent review (see, e.g., Allen, 2013).
However, much work was happening in Russia, and on 18 March 2013 material recovered from the fall was approved by the Meteoritical Bulletin as the "Chelyabinsk" LL5 ordinary chondrite. The total known weight (TKW) recovered on land is said to be over 100 kg, and maybe in excess of 500 kg, in a great number of small fragments. The largest known piece weighs 1.8 kg, and most range from mm to a few cm in diameter. See the Meteoritical Bulletin for technical details (posted 04 May 2013). A "Rock of the Month" feature on the Chelyabinsk meteorite is available now. In October 2013 a large individual mass, >500 kg, was pulled from the murky depth of Lake Chebarkul, and more doubtless remains to be found.
Allen,K (2013) Canadians size up Russian fireball. Toronto Star, A4, 12 April.
Semeniuk,I (2013) "It's a wake-up call", scientists warn. Globe and Mail, A14, 16 February.
Visit the Meteoritical Bulletin and type "Chelyabinsk" (or any other meteorite name) in the search field.
09 February 2013: Today, a very snowy Saturday in southern Ontario, marks the centenary of a remarkable astronomical event. In simplistic summary, a series of fireballs were observed crossing the sky over an improbably long arc, from the Prairies over southern Ontario and the northeast U.S.A., then past the Bahamas, to the Atlantic off the coast of Brazil. While other subhorizontal or glancing visits of bodies to our atmosphere have been reported, this one seems unique. It was dubbed the "Chant Trace" after a professor who described the event at the University of Toronto, and as "The Great Canadian Fireball Procession", since the Canadian observations were the first to be collated.Interpreting this fantastic set of observations is outside our scope here, but if you are interested I have summarized half a dozen articles, published between 1955 and 2010, on the topic. This small annotated bibliography is available as a 64-kb, 3-page file, Chant_trace.pdf. If you have read, or written, the definitive explanation of the Chant Trace, please let us know!
LATEST: Thanks to Damien Lemay and Richard Herd for pointing out two new articles on the event. (1) Donald Olson and Steve Hutcheon undertook the latest in a century-long series of archival quests, and found seven long-forgotten meteorological reports from ships in the south Atlantic, as much as 11,000 kilometres from the most westerly known report in Alberta. Their account appears in the latest issue of Sky & Telescope. I have recently learned of a related exploration of the western, Pacific end of the track: Ricker and Schnute (1999). (2) Ivan Semeniuk wrote a short article on the event for the Globe and Mail newspaper three days ago (06 February 2013). If you track this down, you will read that the latest explanation for the Chant Trace and similar very-rare events is the destruction of a "minimoon". These are apparently asteroidal fragments on dm- to m-scales which are in tentative orbits around Earth, from which they may escape or, alternatively, fall into the atmosphere, as in the 1913 case. As such, they are basically like the meteoroids which come to Earth and drop meteorites, typically losing most of their mass during their fiery entry. Now that's awesome!
Olson,DW and Hutcheon,S (2013) The great meteor procession of 1913. Sky & Telescope, 32-34, February.
Ricker,WE and Schnute,JT (1999) A westward trajectory extension for the Earth-grazing fireballs seen on 9 February 1913. Canadian Field-Naturalist 113, 693-697.
Semeniuk,I (2013) Scientists yearn to catch a moon. Globe and Mail, 1p., 06 February.
05 June 2012: The transit of Venus across the face of the setting Sun was observed by four interested parties from the hilltop vantage point of Pethericks Corners. Despite frequent interruptions by clouds near the northwest horizon, the silhouette of the second planet was clearly visible in the upper right quadrant of the Sun's brilliant disc. It was seen through eclipse glasses, both by eye and via a 200 mm lens on a digital camera. For a detailed account of the significance of this event, just the seventh such transit to be observed in recorded history, see Alan Dyer's article in Sky News 18 no.1, pp.12-19 (May 2012). Additional photographs of the actual transit were published in SkyNews 18 no.3, pp.8-12 (September 2012).
Here is the "skyscape" in the northwest,
about an hour before sunset, and a close-up of the Sun
taken a few minutes earlier,
showing the clear silhouette of Venus (inset: photo by Lisa Winegarden) despite some light cloud.
12 December 2011: A slow-moving fireball was tracked heading northeastward over Lake Erie, past the city of Peterborough, to the vicinity of the hamlet of Selwyn. The fireball was seen by many people, early on that Monday evening, at 18:04 hours local time (well after dark at this time of year). A potential modest meteorite fall is considered likely by experts from the University of Western Ontario's Meteor Physics Group. The likely fall area from the Selwyn fireball is estimated to lie in a SSE-NNW swathe of land running some 25 km northerly from the hamlet of Centre Dummer, across Upper Stony Lake, and beyond the western flank of Petroglyphs Provincial Park, a potential meteorite search area of about 80 km2. For additional details and context see this article. posted 15 December 2011 at: CBC News Technology & Science. It seems a strange coincidence that this is two years to the day since the event described below. It is possible, perhaps, that the earlier event was a very bright example of a Geminid meteor, since that meteor shower peaks around that date (e.g., the night of 13-14 December 2011), but it matched my vision of a possible "meteorite dropper"!
The terrain near Stony Lake will be a challenge to searchers, especially north of the lake, and a day's exploration on 17th December suggested that the best hope may lie with residents, many of them seasonal around lake shores and islands, discovering fragments in spring 2012. Since the remarkably dry early winter period ended with an appreciable fall of snow on the 27th (e.g., some 7 cm of heavy, wet crusted snow in Campbellford), it became certain at that time that any find would be deferred at least until the spring snow melt, and renewed outdoor work on farms and around houses and cabins.
Further road and trail traverses were made, both south and north of the deep eastern ("Upper") part of Stony Lake, and a meteorite I.D. clinic offered, between 29 May and 28 July 2012. Additional traverses were made in the forested, granite-bedrock terrain between Eels Creek and Petroglyphs Park, east and north of High Falls. Further information was gleaned on the lie of the land and the local ecology and geology, but without any finds.
As of noon on the first anniversary of this fireball, Wednesday, 12 December 2012, the writer had not heard any credible reports of a meteorite recovery associated with this event.References
Bajer,E (2011) Researchers hoping to find meteorite. Peterborough Examiner, B7 (15 December).
Baluja,T (2011) Scientists seek meteor shards near Peterborough. Globe and Mail, A14 (15 December).
Black,D (2011) Meteor fall caught on video. Toronto Star, 1p. (15 December).
Cloutis,EA, Hiroi,T, Gaffey,MJ, Alexander,CMO'D and Mann,P (2011) Spectral reflectance properties of carbonaceous chondrites: 1. CI chondrites. Icarus 212, 180-209.
Gordon,K (2011) Meteorite falls near Stoney Lake. Peterborough Examiner, A1-2 (15 December).
Vyhnak,C (2011) Meteorite hunters gear up for Stoney. Toronto Star, GT1,13 (17 December).
A year on from the event discussed above, the Geminid meteor shower peaked on the night of 13 December 2012. At least two casual observers reported multiple meteor sightings on the night of the 12th. Unfortunately, low cloud or ground fog on the 13th hampered our local viewing, with Jupiter alone visible through the haze. In the American Southwest observers were luckier, with peak rates in the order of one per minute.
The Geminids and the January Quadrantids are unique amongst meteor showers in that their origin is ascribed not to streams of ice-and-dust cometary debris but to rocky bodies in near-Earth orbits that approach closely to the Sun. The Geminids are linked to near-Earth asteroid 3200 Phaethon, a rocky body thought in turn to be a fragment detached by an impact event from far-larger main-belt asteroid 2 Pallas.
A further curio becomes apparent by scanning the calendar of historical meteorite falls assembled by Anne Black at www.impactika.com. No falls are noted for the 11-12 December, but four for the 13th December. These are: Wold Cottage (England, 1795, L6 chondrite); Massing (Germany, 1803, howardite); Luotolax (Finland, 1813, howardite); and Vissannapetta (1997, Andhra Pradesh, India, cumulate eucrite). This list is statistically unlikely, given that the last three of the four are variably brecciated achondrite meteorites of the "HED clan", believed to come from asteroid 4 Vesta, representing just 1 in 40 meteorites in the global collection (in contrast L chondrites are the most abundant class, 1 in 3 of known meteorites). It is tempting to speculate that falls at this time of year might be chunks of Phaethon (and, in ultimate parentage, Pallas)! I would not know, though it seems that Phaethon has spectral properties more comparable to the "primitive" carbonaceous chondrite meteorites than to the HED group (Cloutis et al., 2011, p.204).
Older archived material - contacts' links no longer apply.
23 July 2001: Another fireball was seen over a wider area of eastern North America scarcely ten weeks after an earlier sighting, in the early evening of 23 July 2001, the so-called "Pennsylvania bolide" .
06 May 2001: A bright meteor (commonly referred to as a fireball ) was spotted in the region by a few lucky people in the pre-dawn of 06 May 2001. No reported meteorite fall is known to have resulted from either event in 2001.
Weather and other Local Links
Here is a small selection of 60-plus regional places, events and organizations. This is not meant as a travel guide, but simply offers a few clues to the commercial and recreational life and environment of the district. Many are within 20 km of Campbellford, and others are within longer day-trip range, such as Peterborough (roughly 50 km to the west), Bancroft (120 km to the north) or the Sharbot Lake area (150 km to the east).
Local and Regional Weather, News, Radio
With 24 weather-related sites and maps, from regional to continental scale, and beyond:
Environment Canada - Peterborough, Ontario - 5 Day Weather Forecast -- Environment Canada
Weather Underground -- Peterborough
The Weather Network -- Warkworth (Trenton)
Environment Canada - Toronto, Ontario - 5 Day Weather Forecast -- Environment Canada
Environment Canada Weather Radar Map -- King City, north of Toronto
Hydro One (Ontario electric power) with maps of power outages
Buffalo, New York -- Intellicast Regional Weather Radar Map
Environment Canada -- North American Jet Stream / Regional Wind Patterns
Global Jet Stream model
CBC News and Weather portal
Environment Canada Weather - Kitchener-Waterloo
CBC Weather - Ottawa
CBC Weather - Stirling, Ontario
Weather Network - Mattawa, Ontario
Environment Canada Weather Radar Map -- Franktown, near Ottawa
Environment Canada - Sudbury, Ontario - 5 Day Weather Forecast -- Environment Canada
Environment Canada Weather Radar Map -- Britt, between Parry Sound and Sudbury
Environment Canada Weather Forecast Sites -- Ontario
Weather.com Interactive Maps --- North America
NOAA map --- United States and Environs
United States Animated Radar Map
The NASA GOES East Weather Satellite failed on 22 May 2013,
but here is a related image for central-eastern North America
News of the Sun (NASA Solar Dynamics Observatory)
And some local news and information sites:
Toronto Pearson International Airport - YYZ Airport Guide
The Wolf 101.5 FM - CKWF - Peterborough Rock Radio
Satellite Visibility Worldwide
Local Business, Trent Hills area, Northumberland county, Ontario
Trent Hills Tourism --- Local Attractions
Trent Hills & District Chamber of Commerce
Campbellford Business Improvement Area (BIA)
Northumberland County (includes maps)
Heydon Local Business Directory
Bancroft Chamber of Commerce
Municipalities and Districts
Municipality of Trent Hills (includes Campbellford-Seymour area)
The Bancroft District, Ontario
Renfrew County, Ontario / the Ottawa Valley
Municipality of Trent Hills (includes Campbellford-Seymour area)
The Bancroft District, Ontario
Renfrew County, Ontario / the Ottawa Valley
Tourist Attractions and Special Events, 1. Parks and Trails, Natural History
Crowe Bridge Conservation Area (CBCA): Natural History Presentation
Crowe Bridge Park Info
Lower Trent Conservation Authority
LTCA issues "report cards" for a dozen local watersheds, such as Cold Creek, Rawdon Creek and Trout Creek
Lone Pine Marsh Sanctuary & Cora Munn Tract
Friends of Presqu'ile Provincial Park
Parks Canada - Trent-Severn Waterway National Historic Site of Canada
Indian River Reptile Zoo (very good - both for kids, and for scientific value)
The Trans-Canada Trail
Seymour township bird list
Seymour township lists of the local flora and fauna
Drew Monkman: Natural History, Kawarthas District
Terry Sprague's Nature Notes (Prince Edward County)
Tourist Attractions and Special Events, 2. Regional and Local Attractions
Curle's Maple Syrup (farm, shop & museum), Campbellford
Dorset Muskoka and Haliburton Information
Haliburton Forest and Wildlife Reserve Ltd: Canopy Tour & Wolf Centre
Marmora Snofest & Sled Dog Races
- page updated each winter - event held 36 times, 1979-2014
The Alaskan Malamute HELP League (AMHL)
Stirling Festival Theatre
Aron Theatre Co-operative
Ken Tizzard & Bad Intent