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Ther's an graph that appears that the KT asteroid turned the rocks into rubble 3000 km away, else there was a rain of big rocks from the sky.

What are the rip up clasts and what is the way they were generated?

It's at the base of the formation, section 1, lower left.

enter image description here

Log from Tanis Site, North Dakota. Document from PNAS 1

  1. Robert A. DePalma, Jan Smit, David A. Burnham, Klaudia Kuiper, Phillip L. Manning, Anton Oleinik, Peter Larson, Florentin J. Maurrasse, Johan Vellekoop, Mark A. Richards, Loren Gurche, Walter Alvarez, (2019): "A seismically induced onshore surge deposit at the KPg boundary, North Dakota" Proceedings of the National Academy of Sciences Apr 2019, 201817407; DOI: 10.1073/pnas.1817407116
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  • $\begingroup$ Please add where this came from (that will probably explain why you mention North Dakota), and explain how this appears to show...3000 km away $\endgroup$ – Jan Doggen Apr 10 at 13:12
  • $\begingroup$ Yukatan crater to North dakota = 3000km .. Ok i'll add the reference to the OP, i couldnt find it at the time but i had saved the image to my pc as it's so fascinating. google.com/maps/dir/Yucatan,+Mexico/North+Dakota,+United+States/… $\endgroup$ – com.prehensible Apr 10 at 14:58
  • $\begingroup$ Perhaps it's rocks from a mudflow which explains why it's in sandstone, i don't understand why it's graded and where it's from, it's clearly a result of the asteroid impact, it's not very clear. $\endgroup$ – com.prehensible Apr 11 at 19:54
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Short answer: They are clasts from adjacent hillside deposited inmediately after the Chicxulub impact.


The log you posted represents a sudden onshore inundation event due to the impact.

The paper you provided clarifies it [1]:

Tanis site, which documents a turbulently deposited, rapidly emplaced sediment package directly overlain by the Cretaceous–Paleogene (KPg) boundary tonstein. The site, situated in the continental Hell Creek Formation in southwestern North Dakota (Fig. 1), displays inland-directed flow indicators and holds a mixture of Late Cretaceous marine and continental biota, implying that its emplacement is related to sudden onshore inundation surges.

enter image description here

Figure 1: Tanis Site, North Dakota.

enter image description here

Figure 2: Log of Tanis Site, North Dakota.

The unit 1 is described bellow. The contact between conglomerates and the point-bar is non gradational, and the rip-up clasts come from Hell Creek strata above the river (1C).

The base of unit 1 comprises a matrix-supported, massive coarse-sand conglomerate, with angular pebble- to small boulder-sized rip-up clasts derived from the underlying Hell Creek strata. As shown in Fig. 2, the massive sand (1a) at the base of unit 1 has a sharp non gradational basal contact with the underlying point-bar surface and vertically grades into a thin (∼3-cm) zone of plane-parallel bedding of interlaminated sand–silt (lower 1b); climbing ripples (mid 1b); sinuous, wavy lamination (upper 1b); low-angle cross-lamination (lower 1c); fine, discontinuous subparallel lamination (upper 1c); and nearly structureless fine silt/mud near the top (1d). Flow-direction reverses 180° toward the east—seaward—near the top of unit 1

My guess is they were transported to the sand-bar from the hillside because of the sudden event, before the conglomerate clasts started to fall from the sky.


The whole depositional unit took place shortly, and before the iridium layer.

Because the Tanis deposit contains ejecta throughout and is also capped by the KPg tonstein, the depositional event took place during a narrow window of time: after impact but before deposition of the fine-grained KPg tonstein. Given this constraint, we can deduce that the Event Deposit was emplaced within a matter of hours after the Chicxulub impact event.

The subsequent conglomerates are aerial deposits .The event is nicely described at the paper.

We assume a scenario in which ejecta-curtain material, launched at about a 45° elevation angle and seen as the glassy or altered-glass spherules at Tanis, arrived before the shocked quartz that was launched at steep angles in a “warm fireball” produced by release of CO2 from shocked limestone after departure of the ejecta curtain


1 Robert A. DePalma, Jan Smit, David A. Burnham, Klaudia Kuiper, Phillip L. Manning, Anton Oleinik, Peter Larson, Florentin J. Maurrasse, Johan Vellekoop, Mark A. Richards, Loren Gurche, Walter Alvarez, (2019): "A seismically induced onshore surge deposit at the KPg boundary, North Dakota" Proceedings of the National Academy of Sciences Apr 2019, 201817407; DOI: 10.1073/pnas.1817407116

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