A single, but composite, impact ejecta layer in North America, outcropping from New Mexico to Saskatchewan in Canada, clearly shows there has been only one large impact, not two, at the K/T boundary

Brownie Butte, Hell Creek area near fort Peck lake, Montana

The upper layer contains shocked quartz and iridium, the lower layer shards and fragments of spherules, that have been completely altered to clayminerals


move cursor over image, arrow points to the boundery between the two layers

Dogie Creek, near Lance Creek in Eastern Wyoming.

The lower layer here consists of clearly visible spherules, that have all the characteristics of the Chicxulub impact spherules, but have been completely altered to goyazite (the rim) and the interior is either dissolved, or filled with calcite.

The upper layer is rich in shocked quartz and Zircons and contains an iridium anomaly

move cursor over image, arrow points to the boundery between the two layers

Madrid Railroad outcrops, west of Trinidad, Colorado.
move cursor over image, arrow points to the boundery between the two layers

The dark, lowest layer is low-grade coal, upon which rests a grey, 2cm thick layer of tonstein, composed of clayminerals with sparse "ghosts" of impact spherules.

the upper layer, as elsewhere, is rich in iridium, shocked quartz and zircons.

the shocked zircons in the upper layer reveal two ages: One from the time of impact shock (about 65 million years) and another of the age of the continental crust hit by the impact (about 550 million years). As the subsurface of Chicxulub has the same age (pan-african crust) it is highly unlikely that this upper layer is not derived from the Chicxulub impact.

Krogh, T. E., S. L. Kamo, et al. (1993). "Fingerprinting the K/T impact site and determining the time of impact by U-Pb dating of single shocked zircons from distal ejecta." Earth and Planetary Science Letters 119: 425-429.

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A typical example of the impact ejecta layer in the US western interior at the palynological K-T boundary. The ejecta landed in a quiet swamp environment, now trensformed into a coal layer. If there had been no swamp at KT impact time, which often happened, no ejecta layer would have been preserved. At this locality along the railroad tracks, the ejecta layer can be followed uninterupted for over a mile.

If we look closely at the stratigraphy of the layer, one can often observe that the layer actually consists of two layers.

(see Izett, G. A. (1990). "The Cretaceous/Tertiary boundary interval, Raton Basin, Colorado and New Mexico, and its content of shock-metamorphosed minerals; evidence relevant to the K/T boundary impact-extinction theory." Geological Society of America Special Paper 249: 1-100).

It is clearly visible that in the boundary (arrows) between the two sublayers not even a single layer of plantmatter (leaves and such) separates the two layers. This implicates that not a single seasional layer of plantdebris occurs between the two. Let alone that 300.000 years would separate the two layers, and thus the two impacts...........
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Satellite image of the Madrid railroad outcrops

almost all along the entire south side of the railroad cut, the K/T boundary claystone remains visible in the outcrop, invariably just below the massive crevasse splay.

Railroad outcrop, see below
The K/T boundary ejecta layer in the US western Interior