From: Alintelbot@aol.com
Date: Fri Jul 23 1999 - 18:27:20 MDT
Analysis of Landforms in Cydonia Mensa
Crater, H W, McDaniel, S V, Carlotto, M J (P42A-09)
:
Abstract: Analysis of landforms in Cydonia mensa reveals a variety of
features whose probable means of formation is ground-ice and perhaps
liquid water erosion. Some evidence of faulting exists. We examine and
compare some of these landforms. We show that a group of mound-like
formations in the Cydonia area of Mars, of relatively small and nearly
uniform size, have relative positions that repeatedly display symmetries
in the apparent form of related right and isosceles triangles. We also
show that these pairs cluster sharply in density about a certain value
of the defining angle of those related triangles and that on average the
vertices of the triangles lie significantly closer to the measured
centers of the mounds than those for fictitious mounds from a computer
simulation. Our computer simulation of the surrounding features and the
mound formations themselves demonstrates that the numerous examples of
these symmetries, the resultant clustering about certain proportions,
and the relative precision of the vertices to the mound centers are not
compatible with random geological forces. We have thus uncovered an
anomaly of number, geometry and precision. The level of significance we
find for our test is p~15.5/1,000,000 .
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Evidence for a Paleo-Ocean Shoreline, Sedimentary Features and Water
Erosion in Cydonia
Erjavec, J and Brandenburg, J E (P42A-10)
Abstract: Mars Global Surveyor (MGS) images of the Cydonia Mensae region
of Mars have provided evidence that suggests surface water activity of a
long duration. Scarp lines identified by Viking, considered as possible
shoreline features (1), have been reanalyzed using the higher resolution
MGS images. The scarps define a boundary between two different terrain
types, one representing a knobby terrain (highland) and the other a
possible paleo-ocean(2) (lowland). Because of the persistence of the
curvilinear scarps and their offset from the knobby terrain which they
circumvent, they cannot easily be regarded as simple remnants of eroded
knobby terrain. The scarps appear similar to strandline or shoreline
features which occur on earth. That interpretation is supported by the
morphological characteristics of the two terrain types they dissect.
Volcanic flows have been suggested as explanations for many of the
varied terrain types on mars, including kilometers of layered rocks in
the Valles Marineris. In the Cydonia region, volcanic flows are not
likely as land- forming mechanisms. There appear to be no significant
volcanic sources in this region nor can the distinctive erosion
morphologies of many of the landforms in Cydonia be easily attributed to
volcanism. To the contrary, some of the erosion appears to be
structurally controlled, perhaps by faults, layered rocks or even folded
sediments. Furthermore, evidence for both erosion and deposition by
water is strong in Cydonia. Terraces (wave-cut?), benches, probable
sedimentary layering, stream channels and other water erosion features
have been found in the MGS images.
Evidence also exists for both precipitation and surface runoff. Apparent
rills are found on some of the landforms and they appear markedly
similar to rill types found in sedimentary terrains in the western
United States. Still, caution must be taken when using strict
earth-based analogies for martian terrains. If martian terrains
developed under a gravitational field that was only 1/3rd that of the
earth, can we be certain that depositional and erosional environments on
the earth directly correlate to similar environments on mars? Taking
that into consideration and despite strong evidence for water in
Cydonia, we propose that the typical tributary stream networks common on
earth may not be as common on mars on the basis of the different
gravitational field strength.
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Ice Found in Crater in Cydonia
Moore, H L, Brandenburg, J E, Corrick, S, Sirisena, A (P42A-15 )
Abstract: Review of recent Mars Global Surveyor images taken on April
23, 1998 has revealed unusual surface craters located at 40.9 degrees
north latitude and 9.9 degrees west longitude. Unusual crater features
disclosed in the recent MGS Image (strip No.3, Cydonia) indicates that
water ice features may exist in the Cydonia area and appear to correlate
to similar features in Iceland. Specific crater features found include,
a smooth, flat floor surface, high albedo floor surface, a reflection of
the floor surface on the crater wall, no apparent ejecta apron, and
steep crater walls. Several studies have identified and compared surface
features on Mars to like features on Earth, which contain water ice,
including features on the landmass of Iceland (Frey Et Al, 1979; Hodges
and Moore, 1978). Other studies indicate that there is a high
probability of water ice at latitudes greater than 40 degrees north on
Mars (Carr, 1981; Allen, 1979; Soderblom and Wenner, 1978).
Several possible explanations for the presence of water ice in the floor
of the subject crater are presented. Two scenarios presented involve a
meteor or comet hitting the surface and excavating the crater. The
meteor/comet impact is suggested to be significant enough to generate
heat to either: (a) melt water ice in the regolith and bedrock or (b)
crack the crust to permit molten rock to reach close enough to the
surface materials to melt frozen water in the bedrock and soil which
then flowed into the crater and re-froze. This new frozen surface forms
the current flat crater floor.
Another idea presented is the possible daily melting of near surface ice
in the soil and rock. This is supported by recent new evidence from the
NASA Pathfinder project that shows that temperatures on the surface of
Mars reach 20 degrees C. in places, making melting of surface water ice
possible. Also discussed is the possible establishment of a water table
frozen in place at some point in the geologic history of Mars.
(Mac Tonnies)
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