Geoscience Reference
In-Depth Information
Fig. 9.12
Giant flutes cut into
granite on the southern headland
of Mason Bay, Stewart Island,
New Zealand. The flutes point
back to the Mahuika Comet
impact site. The flutes are over
40 m high and were cut by
vortices in flow as the tsunami
went over the headland. Photo
credit Dr. Dallas Abbott,
Lamont-Doherty Earth
Observatory, Columbia
University
Fig. 9.13
Imbricated boulders
stacked against a 30 m high cliff
face on the south side of Gum
Getters Inlet, New South Wales,
Australia. Some of these boulders
are the size of a boxcar. Note the
person circled for scale
level, in the Mahaulepu Caves on the south coast of Kauai
Island, Hawaii facing New Zealand, dated between 1480 and
1610 (Burney et al.
2001
). Fourth, burnt wood, and buried
charcoal and carbon in peats and bogs, have been dated
across the South Island of New Zealand (Mooley et al.
1963
;
McGlone and Wilmshurst
1999
). Dating of this material
spans at least two centuries and terminates at the end of the
fifteenth century concomitant with the peak in meteorite and
comet observations (Fig.
9.3
). Fifth, McFadgen (
2007
) has
comprehensively researched and dated the beginning of the
demise of Maori culture in New Zealand, linking it to one or
more tsunami events at the end of the fifteenth century.
Finally, there is evidence that a comet came close to the
Earth at the end of the fifteenth century. The small and not
very active comet X/1491 B1 (formerly 1491 II) made a
close approach to the Earth on February 13, 1491 (Hasegawa
1979
). Sekanina and Yeomans (
1984
) calculated that a
collision with the Earth was possible around midnight
Eastern Australian time from the northwest, most likely at a
45 angle to the horizon. The direction, season, and time of
day agree with statements made in Aboriginal legends and
our radiocarbon dates. Baillie (
2006
) also recognized the
potential of this comet for an impact with the Earth. He
points out that its timing matches the largest ammonium
spike in a millennium in Antarctic ice cores that can be
interpreted as the signature of a comet impact.
