page_title: Hyperboreae Undae
section_title: Dune characteristics
hierarchical_section_title: Hyperboreae Undae / Dune characteristics
caption_attribution_description: English: Hyperboreae_Undae Today's VIS image shows part of Hyperboreae Undae, a dune field located between the north polar cap and Escorial Crater. This image was taken during northern spring and the dunes still have significant surface frost. The dunes "darken" with time as the frost sublimates from solar heating and the dark sands are revealed.
context_page_description: Hyperboreae Undae is one of the largest and densest dune fields of Planum Boreum, the Martian North Pole. It is named after one of the classical albedo features on Mars. Its name was officially approved by IAU in 1988. It extends from latitude 77.12°N to 82.8°N and from longitude 302.92°E to 316.02°E. Its centre is at latitude 79.96°N, longitude 49.49°W, and has a diameter of 463.65 kilometres.
  Hyperboreae Undae is southwest of the Boreum Cavus depression, an arc-like depression at the northeastern boundary of Chasma Boreale. From there, Hyperboreae Undae continues in a southwestern direction through Chasma Boreale, and into the lowlands of Vastitas Borealis. It overlays the eastern part of Hyperboreae Lingua and the region above Escorial crater.
  Hyperboreae Undae is well known for the barchanoid and linear dunes that have formed at its location, although they are seemingly incompatible. Research has been ongoing to explain the coexistence of these types of dunes at Hyperboreae Undae and elsewhere on Mars. Another type of formation found at Hyperboreae Undae is the yardang.
context_section_description: Although the dunes surrounding the Martian north pole show no signs of movement, two possible exceptions may be the dunes in parts of Abalos Undae, and the dunes of Hyperboreae Undae. In the case of Hyperboreae Undae, the dunes close to its eastern boundary appear to be buried under the Planum Boreum 3 unit. At that area, some of the dunes exhibit dark streaks that may have been caused by katabatic winds. This may indicate sand movement, due to Aeolian activity, which is recent enough to retain the streaks, otherwise these marks tend to disappear with time; other dunes do not exhibit such marks.
  The dunes of Hyperboreae Undae, according to data provided by the Compact Reconnaissance Imaging Spectrometer for Mars, exhibit the weakest signature for the presence of surface ice in the area of Chasma Boreale.  Hyperboreae Undae, along with Abalos and Siton Undae, contributes sand to mainly medium-density dune fields east of Olympia Undae and extending to the Martian prime meridian,
  Image analysis research, using the method of spectral derivatives, has indicated that Hyperboreae Undae, as well as the other dense officially-named northern circumpolar dune fields (Olympia Undae, Abalos Undae, and Siton Undae), show the highest density of gypsum in the area. A geomorphic comparison of Hyperboreae Undae with Rub' al Khali, Earth's largest contiguous dune field, has determined that the morphologies of the two ergs follow similar developmental patterns.
caption: Hyperboreae Undae dunes shown with surface frost. The dunes become darker when the frost sublimates from solar heating and the dark sands are revealed.
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