The Burckle crater is an undersea topographic feature about 29 kilometres (18 mi; 16 nmi) in diameter[1] in the southwestern
Indian Ocean. A team of
Earth scientists called the
Holocene Impact Working Group proposes the feature to be an
impact crater; these claims are disputed by other
geologists.[2]
Burckle Crater's position was determined in 2006 by the Holocene Impact Working Group using prehistoric
chevrondune formations in
Australia and
Madagascar. Based on a
hypothesis that these dunes were formed by a
megatsunami resulting from an impact, the researchers were able to
triangulate the location of Burckle Crater.
In 2009,
geologists Jody Bourgeois and R. Weiss challenged the hypothesis that a megatsunami created the chevron dunes. Using a
computer model to simulate a
tsunami, they argued that the structures are more consistent with
aeolian processes.[3] Other
Earth scientists also dispute the tsunami origin of the chevrons.[2]
Other problems with the claim include:
The Holocene Impact Working Group has suggested that multiple significant
impact events occurred in the past 10,000 years, but
astrononomical models indicate that impact events large enough to cause "hazardous tsunamis" should be expected only about once per 100,000 years, making the Working Group's claims improbable enough that they
call for very strong evidence.[2]
The Working Group bases its claims mostly on the locations of coastal
sedimentary deposits that it has identified and termed "chevrons" and interprets as having been caused by the
run-up from impact-generated megatsunamis. Other geologists assessed them to be
parabolic sand dunes both before and after the Working Group published its findings. The chevrons in Madagascar are precisely aligned with the normal prevailing wind direction at the site as shown by modern weather data, implying that they likely were deposited gradually by wind under present-day conditions as sand dunes, and not by a catastrophic tsunami.[2]
The Working Group reported finding
nickel and
iron splash droplets fused to
foraminiferatests in slides taken from
deep-oceancore samples near Burckle Crater, but this interpretation is problematic because formaminifera tests are made of
calcium carbonate, which chemically decomposes at about 500 °C (932 °F), while nickel and iron melt at temperatures higher than 1,400 °C (2,552 °F). Additionally, comparable splash droplets fused to foraminifera tests have not been reported from any of the
sediment studies performed near the
Chicxulub crater on the
Yucatán Peninsula in
Mexico.[2]
Setting out to identify past impact events by looking for holes in the ground has misled investigators in the past, including the time a
sheepwatering hole in
Italy was called the "
Sirente crater."[2]