Iturralde Crater,
Bolivia
Posted September 10,
2002
large
image:
false color image
NASA
scientists will venture into an isolated part of the Bolivian Amazon to try and
uncover the origin of a 5 mile (8 kilometer) diameter crater there known as the
Iturralde Crater. Traveling to this inhospitable forest setting, the Iturralde
Crater Expedition 2002 will seek to determine if the unusual circular crater
was created by a meteor or comet.
The
team intends to collect and analyze rocks and soil, look for glass particles
that develop from meteor impacts and study magnetic properties in the area to
determine if the Iturralde site, discovered in the mid-1980s with satellite
imagery, was indeed created by a meteor.
If
a meteorite is responsible for the impression, rocks in the area will have
shock features that do not develop under normal geological circumstances. The
team will also look for glass particles, which develop from the high
temperatures of impact.
The
Iturralde Crater Expedition 2002 team will extensively analyze soil in the
impact zone for confirmation of an impact. One unique aspect of the Iturralde
site is the 4-5 km deep surface sediment above the bedrock. Thus the impact was
more of a gigantic "splat" rather than a collision into bedrock.
The
large crater is only 1 meter lower in elevation than the surrounding area.
Water collects within the depression, but not on the rim of the crater, which
is slightly higher than both the surrounding landscape and the interior of the
crater. These subtle differences in drainage are reflected in the forest and
grassland habitats that developed on the landscape. It is precisely these
differences in the vegetation structure that can be observed from space and
which led to the identification of the Iturralde Crater from Landsat Images.
Compare
these images with topographic data from the Shuttle
Radar Topography Mission.
For
more information, visit NASA Scientists Determined to Unearth
Origin of the Iturralde Crater and Iturralde Crater Expedition 2002
Images
by Robert Simmon, based on data from the Landsat
7 Science Team and the Global Land Cover Facility
from
NASA's Earth Observatory, http://earthobservatory.nasa.gov
Follow-up
Data
From Wikipedia, the free encyclopedia
Click
for large Image.
Topographic
image generated from Shuttle Radar Topography Mission data over Iturralde
Crater
Iturralde
Crater (also called Araona Crater) is a 5 mile (8 km) diameter circular
feature in the Bolivian portion of the Amazon Rainforest, first identified from Landsat satellite imagery in
1985.
Being
so circular, it is believed by some scientists that it may be a meteorite impact crater. Because it is in an area of active sediment
accumulation by rivers, it must be a geologically young feature, with estimates
of its age ranging between 11,000 and 30,000 years.
Unlike
other young craters, it is very flat, so if it is of impact origin, perhaps the
crater sunk into the soft sediments leaving only a circular 'ghost' marking the
original rim.
The
site is very remote, but has been visited twice by scientific investigators,
most recently by a team from NASA's Goddard Space Flight Center in September 2002.
In
both cases, the expeditions failed to find conclusive evidence for the origin
of the feature. |
