Table 2

Basic description and morphology of the various regions that are described in the main text.

Region Region type Description Notable feature(s)

Khepry Strongly consolidated Rough- and bright-looking unit neighboring the Imhotep, Aten, Babi, and Aker regions. Moderately lineated. Rough in comparison to Aker although transition to it is gradual. • Numerous ponds of smooth deposits

Aker Strongly consolidated Dark-toned unit with a mixed degree of roughness. Lineated and showing tectonic-like features. Possibly a reworked section of the Khepry region. Several small smooth areas are evident. • 200 m-long angular fractures

Imhotep Non-consolidated: Smooth Geologically the most diverse region on 67P. Extremely smooth, probably recently re-surfaced, yet bouldered region enclosed by horizontally bedded and vertically jointed ridges. There is strong evidence of mass-wasting all around the smooth areas as well as the presence of conical structures and pits that are possibly the result of mechanisms similar to mud volcanism. • Conical mounds • Linear features in enclosed smooth deposits • Field of large boulders

Ash Non-consolidated: Dust-covered Main debris-covered region of the body. Very fine deposits possibly a few meters thick. Similar to Ma’at region. Contains the only currently identified candidate impact crater on the surface of the comet. • Candidate impact crater

Seth Weakly consolidated/Brittle Generally lacking a dust cover, yet bouldered region with ubiquitous circular, semi-circular, and quasi-circular features that display polygonal cracks in some places. Strong evidence of collapse. Possibly underlies the dust in Ash. Sharp topographic contact with Anubis. • Several circular pits • Philae landing site candidate “A” • Chain of active circular pits

Aten Depression Well-defined depression between the Imhotep, Ash, Babi and Khepry regions. Not covered by debris from Ash. Possibly formed through a violent short-term event. • High concentration of talus deposits and rockfalls

Babi Dust-covered/Brittle Transitional region that grades smoothly into Ash and Seth regions in terms of dust cover. Neighbors the Aten, Khepry and Aker regions as well and displays exposures of brittle mantling material at its contact with the Aten depression. • Brittle layered material • Diamond-shaped mesa displaying evidence for mass-wasting and bright boulders.

Apis Strongly consolidated Flat, smooth, and lineated unit showing irregular and polygonal lineations. Significant topographic change with respect to Atum and Imhotep. • Polygonal crack patterns

Atum Strongly consolidated Highly complex region. Minimal bouldering but several small depressions showing some lineation. Irregular complex mounds also seen. Borders the Anubis unit with ill-defined margins in places.

Anubis Non-consolidated: Smooth Smooth region very similar to Imhotep and, possibly, Hapi. Some scattered boulders possibly a result of mass-wasting. Smooth deposits appear faulted/folded in some regions and display linear features similar to those observed in Imhotep. • Linear features similar to Imhotep suggestive of terracing • Fold-like structures.


Hapi Non-consolidated: Smooth Narrow region connecting the head and body of the comet. Currently the most active region and site of regular jet activity although exact source not defined. Smooth dusty-looking material along with dispersed large boulders that may have slumped from the head or body regions. • Linear field of large boulders


Hathor Strongly consolidated A 900 m-high cliff that is opposite to the Seth region on the body and rising above the Hapi region. Un-mantled and heavily lineated in two dimensions. Shows signs of detachment. Lighting makes the lineated appearance appear very uniform but other viewing angles show that it is rough. • Alcove structure with longitudinal terraces • Rectilinear fracture pattern on the cliffs

Anuket Strongly consolidated A complex unit that is separated from Hathor by a scarp. Parallel lineations evident on Hathor are absent. It is separated from Ma’at and Maftet • Peculiar “melted wax”-like overall morphology • 500 m-long linear fracture

Ma’at Non-consolidated: Dust-covered Main dust-covered region on the head. Similar to Ash. Smooth deposits showing ripple-like structures, a possible sign of mobilization. Sharp outcrops of underlying material are usually observed. • Striations or ripple-like features around the rim of Hatmehit

Serqet Strongly consolidated Small region encompassing a sharp ridge and a flat and smooth plain with few boulders.

Nut Depression Small depression between the Serqet ridge and the Ma’at/Hatmehit region. Heavily bouldered. Possible result of erosion of Serqet. Identifiable mostly through topography.


Maftet Strongly consolidated Rough terrain, lineated, and bouldered with scattered patches of debris neighboring the Hatmehit, Nut and Serqet regions. Many small irregular depressions and pits which give the appearance of lifted blocks/chunks of material and possible fluidized activity. • Pit with potentially fluidized outflowing material

Bastet Strongly consolidated Rough and heavily lineated region with minimal bouldering. Borders Hathor and requires anaglyph of the region to identify topographic differences. Separated from Ma’at by showing only limited dust cover. • Oriented lineamints

Hatmehit Depression Well-defined depression in the head region that appears to be filled with fine-grained smooth material overlain by a talus. We use the topography of the edge of the depression to define the region. • Curvilinear ridge traversing the depression floor

Notes. Please refer to the figures in the main text for a visual representation of the extent and boundaries of the different regions.

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