In this sci.astro post I noted unusual parallel trending ridges in an MGS image of the

Tharsis region:

Newsgroups: sci.astro, sci.geo.geology
From: rgcl...@my-deja.com ("Robert Clark")
Date: Mon, 26 Mar 2001 11:15:32 +0000 (UTC)
Local: Mon, Mar 26 2001 6:15 am
Subject: Strange features in Martian craters in Tharsis.
http://groups.google.com/group/sci.astro/msg/5d1bd9437ae5ff52

The ridges appear on the rims of craters, inside craters and within the channel in the image as well:

The ridges have the appearance of de Geer or Rogen moraines on Earth:

Structure of the De Geer moraine and large transversal moraine
ridge at Björköby and Köklot.
http://www.ymparisto.fi/download.asp?contentid=34282&lan=sv

Geonat-project 2003 -2006.
http://en.gtk.fi/export/sites/default/Research/meetings/nordic/image_wintermeeting/breilin_etal_geonat_nettiin.pdf

Moraines.
http://gsc.nrcan.gc.ca/landscapes/pdf/moraines_e.pdf

Rogen moraine: an example of glacial reshaping of pre-existing landforms.
http://www.geol.lu.se/personal/prm/PDF_papers%20full%20text/QSR_2006_Rogen.pdf

A close look at the ridges in the MGS image shows linear indentations cross-wise across their tops. These indentations were mysterious but a Mars Reconnaissance Orbiter image of a region showing similar parallel ridges shows indentations on the ridges that are channels:

Layers with Boulders in Aeolis Region.
http://hiroc.lpl.arizona.edu/images/PSP/PSP_001448_1735/

Look at the highest resolution version available on this page (328 Mbytes) to see the channels running down from the tops of the ridges.
This MRO image is not of the same area as the MGS image, in fact it's on the other side of the planet from Tharsis, but I believe the images show the same type of feature.
The channels have the appearance of water carved features. If the ridges are analogues of moraines then they may be due to melting ice. The boulders in the image may also be glacial erratics, boulders pushed along by the movement of glacial ice.
Moraines can be ice-cored. And the cover of dirt and debris in a moraine can preserve the ice from melting after the original glacier has melted:

Paper No. 33-0
SEDIMENT CHARACTERISTICS OF DIFFERENT TYPES OF ICE-CORED MORAINES, MATANUSKA GLACIER, ALASKA
HEYER, Sean, Geology Department, Augustana College, 639 38th St, Rock Island, IL 61201, ****@augustana.edu.
http://gsa.confex.com/gsa/2002NC/finalprogram/abstract_32762.htm

Recent research has suggested there may be current remnant ice in Tharsis:

Space Sciences
Current glaciers in Tharsis?
Posted by Robert Clark on 11/23/2002 7:26:23 AM
http://habitablezone.com/space/messages/236285.html

Formation of Glaciers on Mars by Atmospheric Precipitation at High Obliquity.
F. Forget,1* R. M. Haberle,2 F. Montmessin,3 B. Levrard,4 J. W. Head5
Science, 20 January 2006: Vol. 311. no. 5759, pp. 368 - 371
http://www.sciencemag.org/cgi/content/full/311/5759/368

The theory is that a debris cover has preserved the ice from melting in this near equatorial region.
Aeolis is contained in the Elysium region which has also been argued might contain relict ice:

Extent and further characteristics of former glaciated terrain in Elysium Planitia, Mars.
J. Nussbaumer, Department of Mineralogy, Natural History Museum, London, UK, ****@nhm.ac.uk.
Lunar and Planetary Science XXXVI (2005) 1949.pdf
http://www.lpi.usra.edu/meetings/lpsc2005/pdf/1949.pdf

Modern shelf ice, equatorial Aeolis Quadrangle, Mars.
Brakenridge, G. R.
Dartmouth Coll., Hanover, NH.
Lunar and Planetary Inst., Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F p 175-176 (SEE N94-12015 01-91)
http://adsabs.harvard.edu/abs/1993LPI....24..175B

Bob Clark