Comets and Asteroids - Tsunami - page 175

Antarctica (Mader 1998 ). Spreading waves from the impact
site would have extended into the North Pacific and Southern
Oceans with a deep-water wave height of 10 m reaching the
most distant coasts. Conservatively, the resulting tsunami
would have been 4, 10, and 20 m high off the coasts of
Japan, California, and New Zealand respectively. Run-ups
would have been amplified by a factor of 2-3 times as the
wave travelled across continental shelves.
Evidence for this tsunami consists of unusual skeletal
deposits of marine and land mammals found mixed on the
Peruvian coast, corresponding to the time of the Eltanin
impact (Gersonde et al. 1997 ). In coastal Antarctica, late
Pliocene deposits of marine sediments containing conti-
nental shelf diatoms have been found several tens of meters
above sea level, also dating from this period. The sediment
layers are less than 0.5 m thick and are analogous to the
splays of shelf sediment described in Chap. 3 , onlapped
onto coasts by modern tsunami. Finally, the splash from the
impact may have lobbed marine diatoms and other micro-
fossils thousands of kilometers into the ice-free Transant-
arctic Mountains of Antarctica. If this is so, then this
evidence may resolve one of the discrepancies between
theory and field evidence for the size of cosmogenically
generated mega-tsunami—namely, that splash may be a
potent force generating some of the geomorphic evidence
attributed to catastrophic flows.

outlines the evidence for tsunami based upon legends cen-
tered on five events: The Deluge Comet 8200 years ago; The
Burckle Flood Comet 4800 years ago, The Mahuika Comet
Event 500 years ago; a Kimberley Event, in northwestern
Australia, less than 500 years ago; and an event in the Gulf
of Carpentaria, northern Australia, 1500 years ago.

9.5.2 Deluge Comet Impact Event

8200 - 200 Years Ago

Kristan-Tollmann and Tollmann ( 1992 ), using legends
collected worldwide, believed that a comet circling the Sun
fragmented into seven large bodies that crashed into the
world's oceans 8,200 ± 200 years ago. This age is based on
radiocarbon dates from Vietnam, Australia, and Europe.
The impacts generated an atmospheric fireball that globally
affected society. This was followed by a nuclear winter
characterized by global cooling. More significantly, enor-
mous tsunami swept across coastal plains and, if the legends
are to be believed, overwashed the center of continents. The
latter phenomenon, if true, most likely was associated with
the splash from the impacts rather than with conventional
tsunami run-up. Massive floods then occurred across con-
tinents. The event may well have an element of truth. Fig-
ure 9.9 plots the location of the seven impact sites derived
from geological evidence and legends. Two of these sites, in
the Tasman and North Seas, have been identified as having
mega-tsunami events around this time. The North Sea
impact center corresponds with the location of the Storegga
slides described in Chap. 7 . Here, the main tsunami took
place 7950 ± 190 years ago. One of the better dates comes
from wood lying above tektites in a sand dune along the
south coast of Victoria, Australia. The tektites are associ-
ated with the Tasman Sea impact and date at
8200 ± 250 years before present. These dates place the
Deluge Comet impact event—a term used by the Toll-
manns—around 6200 BC. This event does not stand alone
during the Holocene. It has been repeated in recent
times—a fact supported by Maori and Aborigine legends
from New Zealand and Australia.

9.5 Events Based upon Legends

9.5.1 Introduction

If cosmogenically generated tsunami are so rare—certainly
within the time span of human civilization, then a paradox
exists because evidence for such events certainly appears
often in the geological record and in human legends. Tra-
ditionally, the difficulty in discriminating between fact and
fiction, between echoes of the real past and dreams, has
discouraged historians and scientists from making infer-
ences about catastrophic events from myths or deciphered
records. Yet, common threads appear in many ancient tales
(Clube and Napier 1982 ; Kristan-Tollmann and Tollmann
1992 ; Masse 1998 , 2007 ; Masse and Masse 2007 ). Stories
told by the Washo Indians of California and by the
Aborigines of South Australia portray falling stars, fire from
the sky, and cataclysmic floods unlike any modern event.
Similar portrayals appear in the Gilgamesh myth from the
Middle East, in Peruvian legends, and in the Revelations of
Saint John and the Noachian flood story in the Bible. These
ancient writings appear to represent meteoritic showers
3000-6000 years ago and, in the case of Aboriginal and
Maori legends events that had they occurred in Europe
would be considered historical. The following section briefly

9.5.3 Burckle Flood Comet Event, 4800 Years

Ago

Independent of the above study, Masse ( 1998 , 2007 ) com-
piled numerous legends indicating that a comet struck the
Indian Ocean about 4800 years ago. He analyzed flood
myths from 175 different cultural groups spanning the
globe, using 12 environmental variables within the body of
great flood myths. These variables took into account sci-
entific evidence for the events leading up to the flood, its