The scientific community still seems divided on the idea of a cometary impact for the Younger Dryas. Some are pursuing this approach, and I found the following article interesting:
New Russian Study Extends the Younger Dryas “Black Mat” to Russia — A Global Cataclysm Confirmed - The Cosmic Tusk
I hope it hasn't already been posted; I did a search and found nothing.
This article probably won't surprise the most distinguished researchers on the forum, but I found it interesting because it provides evidence of impacts during the Younger Dryas in the Baltic region.
This paper is a contribution to the ongoing debate on the nature and drivers of the abrupt environmental shift at the onset of the Younger Dryas
The goal of this study is to identify key parameters ... 12.9–12.8 ka ... in sedimentary sections, and are representative of broader paleobasin dynamics in the eastern Baltic region.
Two new Late Glacial sediment archives ... provide data on this time interval.
Geology, then:
grain size and loss on ignition
change in sedimentation during 12.9–12.8 ka
a peak of terrigenous, coarser-grained material and an accompanying peak of organic matter in sediment
The organic-rich layer in the Kulikovo section, as well as other similar layers in the Baltic, can be considered a “black mat” phenomenon
"Black mat" - "Black matter"
“Black mats” are found at numerous Al-YDB sites on different continents
According to the impact hypothesis, large quantities of organic matter are inferred from increased biotic degradation as a result of the catastrophic impact of environmental and climatic changes
Two major processes could form black mats: the deposition of organic-rich material, as happens in wetlands, for example, and soil formation, possibly due to the weathering of stable, organic-rich landscapes
Regardless of the overarching reason for its genesis, black mats demonstrate sudden and essential changes in environmental ... conditions
This probably indicates an environmental event that caused a short-term increased input and deposition of organic matter, accompanied by a surge in erosional processes
The environmental shift triggered by the event is also recorded in a remarkable drop in pollen concentration and species diversity in the overlying layer.
So, this article highlights one of the many approachs.
YD studies have been extensively focusing on the USA (Carolina Bays, etc) and previous findings allow to pursue the research elsewhere. This seems possible via the focus on "layer X".
Here, it's "black mat layer".
For instance, we know of "the nanodiamond layer" (
here).
Thus, little by little, scientists seem to be successful with this principle of layer:
"Hey, can the black matter layer be found in your measures?"
"And what about the nanodiamond layer?"
So, this allows further studies. Here, the Baltic.
this lithological situation is also characteristic of other paleobasins in the eastern Baltic region and beyond
A review of the published data shows that this lithological situation is characteristic not only for new Late Glacial sedimentary sections (Kulikovo and Sambian sites, Kaliningrad Oblast, Russia) but also for other paleobasins in Lithuania and Poland, as well as central and northern Russia, for layers dated to the onset of the Younger Dryas.
A map of the sites under investigation:
[Some] technical specs:
Five samples from the Kulikovo section and seven samples from the Sambian sequence were subjected to radiocarbon dating
All dates were calibrated to calendar years before present (BP) using the IntCal20 calibration curve
Loss-on-ignition (LOI) analysis included the sequential heating of the samples in a muffle furnace
My post was initially intended to present the article on the "black matter" layer, but I'm taking this opportunity to add some current information about the YD.
During my research on YD, I also came across this type of graph:
This is called the "Bayesian chronological method"; I'm not very familiar with it, but it seems to be a method for aligning and reconciling different measurements found in ice cores, tree rings, etc. I'll post some
unrelated images illustrating this process.
Initially, ice cores, samples, pollens, etc - all show different chronologies:
It's about "the peaks", which are the substantial elements in the samples: a peak indicates an
event.
And so, each serie of samples will feature the peak at different moment:
So, it's about the possibility of aligning the discrepant series.
There was "one" event so those all show the same event (basically).
Overall, this provides a graph of some sort and they can pinpoint a precise date:
I find this very interesting—the scientific community seems to be trying to solve problems using this method, among others—and I hope it will bear fruit!
The idea is that by intelligently combining several measurements, we can define nodes.
Two articles from which I excerpted the above illustrations:
Last bit of info:
Shocked Quartz at the Boundary — and a Plasma Plume in the Backyard - The Cosmic Tusk
For years, critics of the hypothesis demanded two things above all else: “show us shocked quartz at the boundary, and show us an impact crater.” Shocked quartz has always been considered the gold standard of impact evidence ... a crater, of course, is the ultimate calling card of a cosmic impact.
the critics demanded shocked quartz and a crater. The Comet Research Group ... have delivered both.
(...)
And yet, we know what comes next. The small circle of specialists who dug their heels in long ago will likely offer no acknowledgment, no curiosity, and certainly no concession. Dead silence is the expectation.
Let's hope that this won't happen and that there will be some "progress"!
Link to the above scientific article:
Shocked quartz at the Younger Dryas onset (12.8 ka) supports cosmic airbursts/impacts contributing to North American megafaunal extinctions and collapse of the Clovis technocomplex
Pdf:
https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0319840&type=printable
That's all. I'm sorry because I know this won't be of much use to members who specialize in these areas. I hope it will interest novice readers, on the subject of the Younger Dryas.
