Under Construction (UC)
An interesting place to start is with an objective look at plausible scenarios which could have inspired legends such as Phaethon is presenten by Bob Kobres (1993). The Phaeton comet hypothesis model illustrates the final six hours during a close approach of a comet in an Encke type orbit. The scenario simulation shows position of comet over Athens, Greece and its apparent size.  
Comet Phaethon's Ride
by Bob Kobres

For its low density, a comet that is so close to Earth would fragment into millions of meteoroids, spread along its orbit.
The gradual evolutionary processes that shape the Earth have been supplemented in the past by the effects of huge natural catastrophes, such by meteoroids impact stream. The oceans and seas represent much higher percentage of shock surface area.  
An observed thausand palaeolagoons, scars, craters representing the manifestations of perhaps bilions of fragmented cometary bodie stream collision on Earth.  
A meteor shower duration could be short as 2 days long, like Ursids, to a 40 days Taurids or Aquarids, Ophiunchids is a 25 days long. On average, a week is the most common! Thus, the Earth as it approached a torus of meteoroids can traverse an orbit of meetings, lasting from 2 to 40 days. And travel from 5 to 100 million kilometers into the torus of meteoroids from defuncts comets.

The theoretical and observational evidence that, on timescales relevant to mankind, the prime collision hazard is posed by temporally correlated impacts (coherent catastrophism, t ~ 10 2 10 4 yr) rather than random ones (stochastic catastrophism, t ~ 10 5 10 8 yr). The mechanism whereby coherent incursions into and through the terrestrial atmosphere occur is described as being the result of giant cometary bodies arriving in orbits with perihelia in the inner solar system. The relative importance of active and inactive comets in the cratering record, pointing out the potentially significant contribution by disintegrating large comets to the population of inactive Earth-crossers.

Some considerations with regard to large comets:
by Bob Kobres
But such as the Taurid Meteor Stream (Comet Encke is one of these objects) that then get nudged into the inner Solar System, as Earth encounters this stream from time to time, that when Napier and others refer to has comet showers, that the likely duration of the events are over a couple of days (Rod Chilton). Literally a catastrophic event, unlike anything ever happened on the planet. 
The meteoroids of toroid orbit around the Sun in parallel orbits. Each meteoroid has its own orbit, and reach the Earth as parallel meteors. 


Thus, the thousands of comet fragments would form the ponds. The palaeolagoons in many fields present elliptical and aligned distribution, sometimes they are distributed in a chaotic way, sometimes in a filamentary distribution.
 Aligned elliptical stream of palaeolagoons on Australia. A picture of the meteoroids filament distribution on space (?).
Some local groups of scars, ponds, have a same parallel orientation. These palaeolagons may have formed in the same event. On the other hand, many groups have convergent orientation, or divergent. This feature can be explained by the local time (LT) of the event occurrence, or the height of the meteors shower radiant in the sky. This means that setting the orientation of the elliptical ponds may be associated with local time of the cosmic event, if they are origined from the same stream.
Palaeolagoon Geometry
In 2005 during a scientific mission, Italian and Bazilian scientists investigated the Quarí palaeolagoon in São Raimundo Nonato, in Piauí, Brazil, and conducted a sediment lagoon profile. The group identified five (5) units of sediments (U.S.). The US-3: is a Silliceous clasts rocks layer, and could be 12,900 BP old sedment. The clasts are not vulcanic, and are possible impactites.
The excavation (2011) on German small ponds structures gave evidence of very high temperatures in the form of intense melting an glass formation:  matrix-rich breccia - multicolored small rock fragments in a sandy, silty black matrix.
Some crateriform small structures from ten meters in diameters in young sediments in Southeast Germany have raised increased interest in the last decade, although they have been known since longtime. Its possible anthropogenic origin or simple sink holes origin were excluded, detailed rock-magnetic studies point to new ideas focusing on a formation of at least part of the craters are meteorite craters originating from the recently proposed large Holocene so-called Chiemgau impact event.
Most impactites found in impact craters is a type of "breccia".
The impactites are metamorphic rocks of the impact site formed during the cosmogenic process. Therefore, they have varied appearances, depending on the types of rocks from the impact site, temperature and pressure of the ionized gases of the shock wave on the target.
 More about impactites in Panela crater and others.
The Quarí palaeolagoon(s) in Brazil should be the result of range of low density meteoroid impacts.
Many prehistoric cosmic events could be related to the geological and historical neo-catastrophism and NEO research, the hazards to civilization and environment due by meteoroids streams. As a Tunguska like event many palaeolagoons in Brazil could be related to some others Holocene and Pleistocene worldwide events. Perhaps from the same south meteor shower. Ancient lagoons formed from atomic power airblast of south meteoroids stream of a defunct comet.  
 Could an actual meteor shower 45 degree wrapped the South Celestial Pole (SCP) be related to Holocene and End-Pleistocene observed palaeolagoons and scars?
Dynamical models show (2010) that the nodes of 26/P Grigg-Skjellerup came nowhere near Earth's orbit back that time. Back in 1725, the comet was perturbed by Jupiter over several apparitions into a more Earth-approaching orbit, moving the perihelion from near Venus (0.77 AU) to close to Earth (0.99 AU). The Pi Puppid - PPU meteor shower did not exist before 1972, which marks the first time it was observed. The south PPU is not a candidate to be the palaeometeor stream ( 
The south PHO meteor shower is associated to the Blanpain 1819 VI comet, and may be a weak candidate to be the palaeometeor stream.
Dark, dangerous asteroids found lurking near Earth
An infrared space telescope - Wide-Field Infrared Survey Explorer (WISE) - has spotted (2010) several very dark asteroids that have been lurking unseen near Earth’s orbit. Their obscurity and tilted orbits have kept them hidden from surveys designed to detect things that might hit our planet. 
Dark asteroids may be former comets that have long since had all the ice vaporised from their exteriors, leaving them with inactive surfaces that no longer shed dust to produce tails. He points out that many comets have very tilted orbits, and comets visited by spacecraft have been observed to have very dark surfaces.
WISE is expected to discover as many as 200 near-Earth objects – but astronomers estimate that the number of unknown objects with masses great enough to cause ground damage in an impact runs into the tens of thousands.
The Tunguska impact event and beyond
New publication on the cosmogenic palaeolagoons
Agrupación Astronómica de La Safor
Boletin Huygens n. 94 - Enero/Febrero - 2012
2011 - The Tupana Event on VIAJE ALUCINANTE
Description: Talk about the event Tupana, CARL SAGAN, interviewed on CIENCIALCOLE Ignacio Bernabeu and various aspects of scientific disclosure.        MI-Radio Express, audio in spanish.
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