This DTM shows one of the largest craters on the North Polar layered deposits. The lack of larger craters on these deposits is evidence of their youth--erosion and/or deposition have erased older craters.

The North Polar layered deposits and the thinner residual ice cap that covers much of them are among the youngest materials on Mars, composed mostly of water ice. The layering seen on the left side of the DTM is expressed as low ridges and troughs, probably caused by differential erosion of mixtures of water ice and dust. The layering has long been thought to be caused by recent climate changes on Mars, similar to ice ages on Earth. Detailed topographic information on exposures of polar layered deposits such as the one shown here are useful in accurately measuring the thickness of individual layers (Fishbaugh et al., 2010). The sequence of layer thicknesses can then be compared to global climate models.

Over 100 small craters have been found on the north polar deposits using MRO HiRISE and CTX images, most of which are partly filled (Banks et al., 2010). The crater included in this DTM is particularly fresh, and is probably representative of the shape of other craters on the north polar deposits before they were infilled. Therefore it is important to accurately measure the shape of this crater using the digital topography shown here. This information can be used to constrain models of crater degradation and refine our understanding of the recent history of the North polar layered deposits and residual ice cap.

Written by Ken Herkenhoff

References:
Banks, M. E., S. Byrne, K. Galla, A. S. McEwen, V. J. Bray, C. M. Dundas, K. E. Fishbaugh, K. E. Herkenhoff, and B. C. Murray (2010), Crater population and resurfacing of the Martian north polar layered deposits, J. Geophys. Res., 115, E08006, doi:10.1029/2009JE003523.

Fishbaugh, K. E., C. S. Hvidberg, S. Byrne, P. S. Russell, K. E. Herkenhoff, M. Winstrup, and R. Kirk (2010), The first high-resolution stratigraphic column of the martian north polar layered deposits. Geophys. Res. Lett. 37, L07201, doi:10.1029/2009GL041642.