If the cometary impact opens the doorway of time on one end, what opens the doorway of time on another end? Another cometary impact in that time?
A confluence of circumstances that makes such a 'doorway' easy to open itself?
We conceive of time being something that is a flow from moment to moment, but I find very little thought on how the dimension of time is related to the three dimensions of space. Perhaps our attachment to horological devices, and the earth's near constant orbital rotation and period, essentially make this sort of illusion persistent.
But if this flow of time was not a linear progression, rather more like a stacking progression, sort of how you would stack 2 dimensional sheets of paper into a stack, or say a 3-dimensional layering like an onion, or a 4 dimensional undulation of a sphere known mathematically as a
3-sphere, you then technically wouldn't need much to disturb the arrangement of the flow, or the presentation of time at any moment recorded for all eternity on a planet. All you would need to do, is say eject enough of a harmonized current into some apparatus that generates some form of electromagnetic field, technically, or naturally, for such possibilities to maybe present themselves.
The guy at the Why Files presented some of his researched cryptid stories to be essentially sitting around the confines of underground caves, aquifers and water systems that have a grounded affinity, and interact with the electromagnetic system of the planet, producing fields of different variety as compared to those in more human based areas, in the video below:
It might be trifling, if it not were for another Youtuber, Bob Gymlan, writing up a viewer submitted story about a time-portal being opened, with the viewer and her relative being "transported" briefly but straight into the
Carboniferous period, with massive dragonflies and such. That being the first narrative that Bob presented in this video below:
Something akin to this artistic rendition of the geologic period:
Of course, with everyone basically having a camera these days, we should have seen at least significant evidence of these time portals doing their thing ... ... ...
But this
find by
@Ricardo might be what you're looking for, if humans ever got down the technical details and technique of that sort of thing. (the html jumps around a bit, so you'll need to refresh the page once every embedded thing gets loaded in

).