Tubes on Mars
All the segments of image m0001504, titled
Lobate bright/dark contacts on Acidalia
Planitia have features that strongly suggest glacial activity. For instance, many
small depressions look as if they contain ice. I, for one, do not believe an impact
crater created every hole on Mars. Many processes leave holes behind, like dolines,
karst lakes and kettles to name a few.
Kettles are depressions in glacial deposits (drift). A depression forms when a mass
or large block of buried ice melts. Kettles can be large and often contain lakes. Presently on Mars
kettles would contain ice. It is possible that, along with sinkhole plains,
caves, thermal karst, etc., Mars had kettle lakes and landscapes resembling the
region around the Great Lakes of the US and Canada. Kettles are commonly associated with Kames.
Kames are mounds, knobs or ridges of stratified glacial drift. There are several ways to
make a kame: Stream deposits of subglacial channels - in much the same way as normal surface
streams. Fans and deltas are common subglacial stream deposits. Deposits from streams on top the glacier
that empty into holes or crevasses. And from sediment and materials that come to rest
on top of stagnant ice or in superglacial ponds, ditches, crevasses, etc. These deposits are left
behind when the glacier retreats.
Kame terraces are stream deposits between valley walls or lateral moraines
and masses of retreating ice, such as melting glaciers, glacial tongues or a body of slow moving 'stagnant' ice.
A stream tends to sort and deposit materials according to grain size and its ability to
transport its load.
This is how stratified layers develop. After the glacier is gone, stratified deposits of
sand and gravel remain in terrace like ridges.
Similar to kames, eskers are long narrow sinuous ridges. They form under
stagnant or retreating glaciers which have very active subglacial streams. Their sinuous
pattern reflects the meandering channels that made them. Eskers often come in pairs,
as there are two sides of the stream. After the glacier is gone a lake is often left
between a pair of eskers.
These structures are commonly found together, in hilly hummocky glacial
topography - vast areas (fields and valleys) of kames, kettles, lakes, streams,
ponds, eskers, terraces, ridges, flutes, polygonal ground, and various types of moraines.
Acidalia Planitia seems to exhibit this topography. Perhaps it was glaciated.
If it were, then after the ice retreated, or melted because of some catastrophic event,
the land would lose the support it had for so long.
Deformation, isostatic rebound, slumping and collapse are sure to follow after all that
pressure is gone. You can think of a kettle in this way. The ice leaves
and the land collapses. Or the ice melts and remains in the
collapsed space as a lake. A Kame terrace, or part of it, will slump or collapse when
the retaining ice walls are no longer supporting it.
Is it possible that the worm/tube shapes formed in such a glacial,
or semi-glacial, enviornment?