A6. The Quads – North Mid Latitudes
Elevation context. The band straddles the dichotomy boundary (Alpha–Epsilon margins) and the northern lowlands (Beta–Delta–Zeta cores), with typical surface levels ~1–5 km below the areoid in the plains, rising locally over Tempe/Alba.
Climate/“weather. Expect large diurnal temperature ranges, seasonal CO₂ frost, and dust-driven variability in visibility and insolation. The deeper lowlands (e.g., Utopia/Arcadia/Acidalia) tend to have higher ambient pressure than adjacent uplands at the same latitude. (General Mars climatology; plain-lowland pressure context)
Volatiles/ground ice. Multiple lines of evidence indicate shallow ground ice or excess ice across portions of Arcadia and Utopia in this latitude band; Phoenix confirmed water ice in the high-north ground.
⬛ Alpha (30–72°N 0–60°E)
Profile. A classic dichotomy-boundary sector dominated by fretted terrains—corridors of mesas and buttes separated by smooth lowlands—between the southern highlands and the northern plains. Major provinces include Deuteronilus Mensae (~44°N, 27°E) and Protonilus Mensae (~44°N, 45–50°E).
Relief & elevation. Transitional topography stepping down from cratered uplands to the lowlands; fretted scarps typically ~1–2 km high.
Geology & landforms. Extensive fretted terrain with lobate debris aprons, rock-glacier–like flows, lineated valley fill, and dissected plateaus (hallmarks of cold-climate modification).
Surface texture. Mantled slopes, polygonized ground in places, aprons with flow lineations; smooth lowlands juxtaposed with steep-walled troughs.
Weather/temperature tendencies. Mid-latitude regime with strong diurnal ranges and seasonal CO₂ frost; local katabatic/upslope winds along scarps can focus dust/sand transport. (General mid-latitude behavior)
Notable observations. Numerous HiRISE/THEMIS campaigns document glacial/periglacial morphologies and active mass-wasting along the mensae.
⬛ Beta (30–72°N 60–120°E)
Profile. Encompasses much of western and central Utopia Planitia—the vast northern plain filling the Solar System’s largest recognized impact basin; includes periglacially modified lowlands with patterned ground and thermokarst-like textures.
Relief & elevation. Broad, low-lying plains (many areas ~4–5 km below datum) with subdued cratering and wrinkle ridges. (Vastitas-style lowland context)
Geology & landforms. Smooth plains with periglacial indicators (scalloped depressions, polygonal ground, possible ice-rich mantles); locally, pedestal and thermokarst-like craters.
Surface texture. Dusty veneers and sand sheets interspersed with armored or indurated patches; low relief over long distances.
Weather/temperature tendencies. Large daily thermal swings moderated by dust loading; seasonal pressure changes are noticeable in this elevation range.
Notable observations. Viking 2 landed in Utopia Planitia (46.7°N, 117.5°E); Zhurong also landed on the basin’s southern margin (both in the wider Utopia region).
⬛ Gamma (30–72°N 120–180°E)
Profile. Eastern Utopia into the northern mid-latitudes, with Galaxias Fossae troughs and parts of the high-latitude Scandia province toward the 70°N limit.
Relief & elevation. Lowland plains punctuated by graben/fossae (e.g., Galaxias Fossae centered near ~36–39°N, ~218°E), plus scattered volcanic/sedimentary constructs.
Geology & landforms. Tectonic troughs, channels, and flow features along the Utopia margin; toward high latitudes, Scandia Cavi/Tholi fields (pitted, collapse/volcanic constructs) approach the polar dune seas.
Surface texture. Mixed smooth plains and fractured/graben terrain; localized dune patches.
Weather/temperature tendencies. Similar mid-latitude swings; proximity to high-latitude dune fields hints at frequent dust/sand mobilization episodes.
Notable observations. Viking 2’s site (48°N, 225°W ≡ 135°E) lies in this longitude sector of Utopia. (Landing context)
⬛ Delta (30–72°N 180–240°E)
Profile. Dominated by Arcadia Planitia (≈ 34–64°N, 166–210°E) — a northern lowland plain northwest of Tharsis — plus surrounding transitional terrains. This quad is notable for widespread shallow subsurface ice.
Relief & elevation. Broad plains mostly ~2–4+ km below datum; very low regional slopes. (Lowland context)
Geology & landforms. Radar and crater-terrace studies show excess ice bodies ~30–80 m thick in Arcadia; expanded secondary craters and thermokarst-like features suggest volatile-rich substrates.
Surface texture. Smooth to gently undulating plains with sand sheets, megaripples, and occasional wrinkle ridges; polygonized mantles in places.
Weather/temperature tendencies. Strong diurnal ranges; dust events can flatten the day–night contrast; Phoenix (68.22°N, 234.25°E) documented near-surface water ice just beneath the soil.
Notable observations. Phoenix excavated and imaged water ice at high northern latitudes within this longitude band.
⬛ Epsilon (30–72°N 240–300°E)
Profile. A transition from lowlands into the tectono-volcanic margin of Tharsis: includes Alba Mons (a giant, very low-slope shield centered near ~40°N, ~251°E) and large swaths of Tempe Terra, a highly fractured highland block at Tharsis’ NE edge.
Relief & elevation. Alba Mons summit reaches ~6.8 km above datum with extremely low flank slopes; Tempe Terra stands higher than adjacent lowlands and is heavily faulted/grabenated.
Geology & landforms. Alba: vast lava aprons, collapse pits, radial/annular fractures. Tempe Terra: dense arrays of normal faults, graben (Tempe Fossae), small shields, and lava flows—one of Mars’ most crustally strained regions.
Surface texture. Rocky lava plains, tectonic lineaments, and interspersed dust/sand mantles; local dune patches on benches and in troughs.
Weather/temperature tendencies. Elevated, rougher terrain fosters gusty afternoon winds and channeling; thermal inertia contrasts produce strong local day–night temperature variability.
Notable observations. THEMIS/HiRISE imaging catalogs abundant faults and volcanic constructs across Tempe and the Alba flanks.
⬛ Zeta (30–72°N 300–360°E)
Profile. From the eastern Tempe Terra margin into Acidalia Planitia—a smooth, dark-toned lowland plain north of Chryse, receiving outflows from Kasei and neighboring systems (lower latitudes). This quad showcases the muted, smooth northern plains and enigmatic mounded terrains.
Relief & elevation. Generally low-lying plains several kilometers below datum; long, gently rolling horizons typical of the northern lowlands. (Vastitas/Acidalia context)
Geology & landforms. Acidalia Planitia: smooth plains with low crater densities, wrinkle ridges, and enigmatic mounds (proposed mud-volcano or spring mounds in parts). Eastern Tempe Terra contributes fault-bounded blocks and erosional benches near 30–40°N.
Surface texture. Dusty to sand-mantled surfaces with broad sheets and streaks; localized dune fields in depressions; widespread low-albedo patches.
Weather/temperature tendencies. Frequent dust hazes modulate light; large diurnal swings typical of lowlands; outflow-channel aprons (south of 30°N) grade to smoother plains here.
Notable observations. Decades of MOLA/THEMIS/HiRISE work underpin interpretations of Acidalia’s resurfacing history and smoothness.