Within Duhamel
Did a 135 Ton Craft Land at Duhamel?
The famous 135-ton figure was a rough pressure estimate based on assumptions, not proof that a massive craft rested in the field.
On this page
- How the pressure estimate was calculated
- The assumptions behind simultaneous circular loading
- Why a much lighter rolling device remained possible
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Introduction
The frequently repeated claim that a 135-ton craft landed at Duhamel, Alberta, is one of the most persistent misunderstandings associated with the 1967 case. The number did appear in an official investigation, but it was never presented as evidence that a 135-ton object had actually been present. Instead, it was a rough engineering calculation exploring one possible way the circular ground marks might have been produced under a specific set of assumptions.[Library and Archives Canada]gc.caLibrary and Archives Canada Onsite inspection of reputed UFO landing marks at Duhamel, AlbertaLibrary and Archives CanadaOnsite inspection of reputed UFO landing marks at Duhamel, AlbertaJanuary 8, 2018
Understanding how that estimate was derived is important because it changes the meaning of the evidence. The investigator was testing a hypothetical loading scenario, not measuring the weight of an unknown craft. The same report also concluded that the marks could have been produced by a much lighter rolling wheel under different conditions and that neither a hoax nor any other explanation could be confirmed or ruled out.[Library and Archives Canada]gc.caLibrary and Archives Canada Onsite inspection of reputed UFO landing marks at Duhamel, AlbertaLibrary and Archives CanadaOnsite inspection of reputed UFO landing marks at Duhamel, AlbertaJanuary 8, 2018
How the pressure estimate was calculated
The famous figure originated in the Department of National Defence inspection of the Duhamel site. Investigator G. H. S. Jones examined the circular impressions and attempted a simple engineering estimate of the pressure that would have been required to leave visible marks in the soil.
His reasoning worked broadly as follows:
- He estimated that approximately 50 pounds per square inch (psi) would be needed to produce the observed impressions.
- He treated one of the rings as a continuous circular contact area roughly 30 feet in diameter and about five inches wide.
- Multiplying the estimated contact area by the assumed pressure produced a total load of about 270,000 pounds, or approximately 135 tons.[Library and Archives Canada]gc.caLibrary and Archives Canada Onsite inspection of reputed UFO landing marks at Duhamel, AlbertaLibrary and Archives CanadaOnsite inspection of reputed UFO landing marks at Duhamel, AlbertaJanuary 8, 2018
Jones described this as being “in the right ball park” for a large aircraft or, speculatively, a small spacecraft. Crucially, this was not presented as a measured weight. It was simply the result of combining assumed pressure with an assumed contact area under one particular model.[Library and Archives Canada]gc.caLibrary and Archives Canada Onsite inspection of reputed UFO landing marks at Duhamel, AlbertaLibrary and Archives CanadaOnsite inspection of reputed UFO landing marks at Duhamel, AlbertaJanuary 8, 2018
The assumptions behind simultaneous circular loading
The calculation depends on several assumptions that cannot be verified from the surviving physical evidence.
First, it assumes that the entire circular ring carried weight simultaneously, as though a rigid circular landing pad rested on the ground all at once. If that assumption is wrong, the resulting load estimate changes dramatically.
Second, the assumed soil pressure was itself only an approximation. Jones explicitly described the calculation as a rough estimate made during a relatively quick investigation rather than a precise geotechnical analysis. The actual pressure required to leave impressions would vary with soil moisture, vegetation, compaction and the duration of loading, none of which could be measured accurately after the site had already been disturbed.[Library and Archives Canada]gc.caLibrary and Archives Canada Onsite inspection of reputed UFO landing marks at Duhamel, AlbertaLibrary and Archives CanadaOnsite inspection of reputed UFO landing marks at Duhamel, AlbertaJanuary 8, 2018
Third, the geometry of the contact area was simplified. Small changes in the estimated ring width or pressure produce large changes in the calculated total load because the estimate scales directly with the assumed area of contact.
These uncertainties mean that the figure should be understood as an illustrative engineering exercise rather than a reliable estimate of an object’s mass.
Why a much lighter rolling device remained possible
The same report that introduced the 135-ton calculation also discussed an alternative mechanism requiring far less weight.
Jones concluded that the marks could have been produced by a wheel in rolling contact, provided it carried a load of at least about half a ton and was moved carefully in an almost perfect circle. In other words, the report explicitly recognised that a moving wheel concentrated its load into a much smaller contact patch than a stationary circular base, requiring far less total weight to generate similar local pressures.[Library and Archives Canada]gc.caLibrary and Archives Canada Onsite inspection of reputed UFO landing marks at Duhamel, AlbertaLibrary and Archives CanadaOnsite inspection of reputed UFO landing marks at Duhamel, AlbertaJanuary 8, 2018
This distinction is often lost in later retellings.
A stationary ring distributes force around its entire circumference simultaneously, requiring a very large total load to achieve high pressure everywhere at once.
A rolling wheel applies similar pressure only to the small section touching the ground at any given moment. Because the contact area is tiny, the total vehicle weight can be vastly lower while still producing comparable impressions.
The report therefore offered two fundamentally different mechanical possibilities, not one definitive conclusion about an enormous landed craft.
Why later retellings exaggerate the evidence
Popular UFO books and websites frequently cite “135 tons” as though investigators determined the weight of an unidentified vehicle from physical traces. That is not what the official report says.
The original investigation reached much narrower conclusions:
- the origin of the marks remained unexplained;
- a hoax could neither be confirmed nor excluded;
- rolling-wheel production remained mechanically plausible;
- a stationary circular support might require something in the range of roughly 100–200 tons under the investigator’s assumptions, but this was only a hypothetical calculation.[Library and Archives Canada]gc.caLibrary and Archives Canada Onsite inspection of reputed UFO landing marks at Duhamel, AlbertaLibrary and Archives CanadaOnsite inspection of reputed UFO landing marks at Duhamel, AlbertaJanuary 8, 2018
Removing those qualifications transforms a conditional engineering estimate into an apparently precise measurement, which overstates what the evidence can support.
What the 135-ton figure really tells us
Within the wider Duhamel case, the 135-ton estimate remains interesting because it demonstrates that Canadian defence investigators took the physical traces seriously enough to analyse them quantitatively. It does not demonstrate that an object of that mass landed in the pasture.
The most balanced reading is that the calculation explored one possible explanation for the observed ring geometry. Because the underlying assumptions cannot be verified and because the investigator also recognised lighter rolling mechanisms as plausible, the figure should not be treated as proof of a massive landed craft.
That distinction matters when assessing Duhamel’s place in Alberta’s UFO history. The case remains noteworthy because unusual ground traces were officially investigated and ultimately left unresolved—not because investigators established that a 135-ton unidentified vehicle had rested on the site.[Library and Archives Canada]gc.caLibrary and Archives Canada Onsite inspection of reputed UFO landing marks at Duhamel, AlbertaLibrary and Archives CanadaOnsite inspection of reputed UFO landing marks at Duhamel, AlbertaJanuary 8, 2018
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Endnotes
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Library and Archives CanadaOnsite inspection of reputed UFO landing marks at Duhamel, AlbertaJanuary 8, 2018...
Published: January 8, 2018
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