Icy Layers and Climate Fluctuations at the Martian North Pole
NASA/JPL-Caltech/UArizona
Icy Layers and Climate Fluctuations at the Martian North Pole
ESP_016973_2595  Science Theme: Seasonal Processes
Sometimes icy layers can be ablated away during warm climates. Later the ice sheet can be buried by new ice layers and grow in size again; it's likely that many of these cycles have occurred over the ice sheet’s history.

The Martian North Polar layered deposits are an ice sheet much like the Greenland ice sheet on the Earth. Just as with the ice sheet in Greenland, this Martian ice sheet contains many layers that record variations in the Martian climate.

These sorts of fluctuations in the thickness of the ice sheet are most pronounced at the edges of the sheet where this HiRISE image was taken. The ice sheet ends here in a gentle scarp that slopes about eight degrees downhill from bottom to top in this image. The layering within the ice is exposed on this sloping surface; the thickness of the ice here is about 1 kilometer (about 3300 feet). Scientists are analyzing these layers to see what information they might hold regarding previous Martian climates.

Most of the layers are parallel to each other. However, if you look more closely at the layers near the base of the slope then you can see that they are orientated at odd angles to each other. This happens when the ice sheet undergoes the fluctuations in thickness described above. Ice is ablated away and the new ice sheet surface cuts at an angle through several layers. When ice starts being laid down here again, it is in layers parallel to the surface and so at an angle to the older layers. Much later this sloping surface was created by erosion and gives us a cross-sectional view of all the layers and the angles they make with each other. When sloping layers are truncated by flat ones like this geologists call it an angular unconformity.

This location is especially interesting because the ice sheet partly covers an impact crater that is about 17 kilometers (about 10 miles) diameter. You can see the rim of this crater on the flat terrain in the top quarter of the image. The curving crater rim is partly buried by the ice sheet here. The slopes within the crater caused the lowest elevation ice layers to be tilted and probably led to the abundance of angular unconformities at this location.

Written by: Shane Byrne  (31 March 2010)
 
Acquisition date
11 March 2010

Local Mars time
14:07

Latitude (centered)
79.304°

Longitude (East)
351.461°

Spacecraft altitude
316.9 km (197.0 miles)

Original image scale range
31.8 cm/pixel (with 1 x 1 binning) so objects ~95 cm across are resolved

Map projected scale
25 cm/pixel

Map projection
Polarstereographic

Emission angle
1.6°

Phase angle
60.2°

Solar incidence angle
59°, with the Sun about 31° above the horizon

Solar longitude
62.4°, Northern Spring

For non-map projected images
North azimuth:  106°
Sub-solar azimuth:  319.3°
JPEG
Black and white
map projected  non-map

IRB color
map projected  non-map

Merged IRB
map projected

Merged RGB
map projected

RGB color
non-map projected

JP2
Black and white
map-projected   (1050MB)

IRB color
map-projected   (442MB)

JP2 EXTRAS
Black and white
map-projected  (557MB)
non-map           (432MB)

IRB color
map projected  (168MB)
non-map           (367MB)

Merged IRB
map projected  (248MB)

Merged RGB
map-projected  (246MB)

RGB color
non map           (322MB)
ADDITIONAL INFORMATION
B&W label
Color label
Merged IRB label
Merged RGB label
EDR products
HiView

NB
IRB: infrared-red-blue
RGB: red-green-blue
About color products (PDF)

Black & white is 5 km across; enhanced color about 1 km
For scale, use JPEG/JP2 black & white map-projected images

USAGE POLICY
All of the images produced by HiRISE and accessible on this site are within the public domain: there are no restrictions on their usage by anyone in the public, including news or science organizations. We do ask for a credit line where possible:
NASA/JPL-Caltech/UArizona

POSTSCRIPT
NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate, Washington. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona.