A7. The Quads – North Low Latitudes

Elevation context. Much of the band lies at or below the areoid in basins and plains (Isidis, Amazonis, Chryse–Acidalia), increasing ambient pressure relative to highlands; volcanic rises (Tharsis/Elysium/Olympus) punctuate this low-latitude belt.

Geodynamic themes. Shield volcanism (Tharsis, Elysium), young flood lavas (Amazonis, Athabasca), and mega-outflow channels (Kasei system to Chryse) dominate, with carbonate- and clay-bearing terrains (Nili Fossae/Jezero) recording ancient aqueous alteration. 

Atmosphere–surface interplay. Large diurnal temperature ranges at low latitudes; dust activity (haze to storms) strongly modulates illumination, thermal structure, and surface visibility across the plains. (General Mars behavior consistent with cited regional datasets.)

⬛ Eta (η) (0–30°N, 0–60°E)

Profile. Dominated by the western half of Arabia Terra, an ancient, high-standing upland marked by deeply eroded, densely cratered terrain and widespread layered sedimentary mounds inside craters. The quad straddles the northern edge of the cratered highlands as they slope toward the northern lowlands. 

Relief & elevation. Broad uplands relative to the northern plains; subdued but extensive relief with crater rims, mesas, and knobs. 

Geology & landforms. Repeated layering (often meter-scale) in crater mounds; pedestal craters and erosional benches; yardang-like wind sculpture in softer units. Layer origins include dust/sediment accumulation and chemically precipitated deposits. 

Surface texture. Heavily mantled slopes, degraded craters, and patchy induration; frequent dust veneers. 

Weather/temperature tendencies. Typical low-latitude large diurnal temperature ranges; dust hazes common but highly variable seasonally. (General Mars climatology for 0–30°N.)

Notable observations. Arabia Terra’s layered sequences are a key archive of ancient environmental cycles recorded from orbit at HiRISE resolution.

⬛ Theta (θ) (0–30°N, 60–120°E)

Profile. A geologically diverse sector including Syrtis Major Planum (dark, low-relief shield volcano), the Isidis Planitia impact basin, and the Nili Fossae–Jezero region with widespread carbonate-bearing and hydrated silicate rocks. 

Relief & elevation. Isidis is a ~1,200–1,325 km basin along the dichotomy boundary (low-lying interior ringed by uplifted rims); Syrtis Major rises slightly as a broad shield to the SW. 

Geology & landforms. Syrtis Major: basaltic shield with calderas (e.g., Nili Patera); abundant dikes/inverted relief. Isidis margin & Nili Fossae: extensional graben and Mg-carbonates (magnesite) associated with altered olivine; widespread phyllosilicates.  Jezero Crater: paleo-lake basin with a deltic fan (Perseverance landing site; 18.4°N, 77.5°E) at the NW Isidis rim. 

Surface texture. Mix of smooth basin plains (Isidis) and rough, fractured terrains (Nili Fossae); aeolian bedforms are common on open plains. 

Weather/temperature tendencies. Basin floor pressures above areoid norms; dust optical depth changes rapidly with regional storms from Syrtis/Isidis corridors. (Context from MOLA/atmospheric scaling.) 

Notable observations. Perseverance’s campaign has documented deltaic stratigraphy and carbonate–olivine terrains relevant to Mars’ early aqueous history. 

⬛ Iota (ι) (0–30°N, 120–180°E)

Profile. Encompasses the Elysium volcanic province—Elysium Planitia/Mons—and the tectonic–volcanic Cerberus Fossae fissures that source Athabasca/Marte Valles. The InSight lander touched down on Elysium Planitia (4.5°N, 135.9°E), a flat, rock-poor sand and pebble surface ideal for geophysics.

Relief & elevation. Very low-slope plains broken by wrinkle ridges and young lava flow margins; Elysium Mons (~25°N, 147°E) rises to the north. 

Geology & landforms. Cerberus Fossae: youthful extensional fissures tied to marsquakes; sources for lava and outflow channels.  Athabasca Valles & flood lavas: extremely young surfaces (Amazonian) with thin, extensive flood basalts draping channels; lava thicknesses commonly tens of meters. 

Surface texture. Smooth to gently hummocky lava plains with sparse rocks and few large dunes near the InSight site; local yardangs and pressure-ridge lava textures. 

Weather/temperature tendencies. Equatorial insolation with large day–night swings; regional dust storms occasionally lower light and reduce thermal contrast.

Notable observations. InSight detected marsquakes dominantly from the Cerberus Fossae region and tied several to fresh impacts. 

⬛ Kappa (κ) (0–30°N, 180–240°E)

Profile. A classic volcanic–plains sector: Amazonis Planitia (among the smoothest plains on Mars) and the eastern apron of Olympus Mons with its towering basal scarp and aureole deposits. Parts of the western Medusae Fossae Formation (MFF) extend into this longitude band. 

Relief & elevation. Low-lying, extremely smooth plains across Amazonis punctuated by wrinkle ridges and lava margins; Olympus Mons rises ~21–22 km above surrounding plains, with an escarpment locally up to ~8–10 km high. 

Geology & landforms. Young Amazonian lavas and mantles; Olympus Mons shield with lobate aureole/landslide deposits; MFF forms wind-sculpted, easily eroded deposits of probable volcanic/airfall origin. 

Surface texture. Vast, planar to gently hummocky lava plains with sparse crater populations; local lava channels/levees and megaripples where sands accumulate. 

Weather/temperature tendencies. Open lowlands yield comparatively higher ambient pressures than adjacent uplands; regional dust hazes frequent but variable. (MOLA/pressure context.) 

Notable observations. Amazonis’ youth and smoothness are well documented in regional mapping; Olympus Mons’ aureole/escarpment system remains a key case study in megaslides and volcano–substrate interactions. 

⬛ Lambda (λ) (0–30°N, 240–300°E)

Profile. The NE Tharsis flank and adjoining Lunae Planum, including Ascraeus Mons (~12°N, 255°E) and Pavonis Mons (~0.8°N, 247°E). At the NE margin, Echus Chasma—a tectono-volcanic trough—forms the source region of Kasei Valles, one of Mars’ largest outflow channels. 

Relief & elevation. High volcanic rises transition eastward to lava-mantled plateaus (Lunae Planum), then break into troughs and channel heads; cliffs at Echus can reach ~4 km. 

Geology & landforms. Tharsis Montes (Ascraeus/Pavonis): enormous shield volcanoes with radial/annular fractures and extensive lava aprons; fan-shaped deposits on flanks.  Echus–Kasei system: tectonic troughs feeding Kasei Valles, with evidence for staged aqueous flooding later overprinted by basaltic lavas. 

Surface texture. Rocky lava surfaces on volcano flanks; smoother Lunae Planum plains with wrinkle ridges; erosional benches and streamlined forms within channel corridors. 

Weather/temperature tendencies. Strong afternoon upslope/downslope winds along volcanic slopes; dust loading modulates diurnal contrasts on adjacent plains.

Notable observations. THEMIS/HRSC campaigns capture Echus’ canyon headwalls and the upper Kasei reaches; long-baseline USGS mapping defines the Lunae Planum plains framework. 

⬛ Mu (μ) (0–30°N, 300–360°E)

Profile. A northern lowland sector receiving the termini of major outflow systems: Chryse Planitia (Viking 1 landing) and the southern Acidalia Planitia (site of enigmatic mounded terrains). Channels including Kasei, Maja, Tiu, Simud, and Ares Vallis (Pathfinder landing) debouch here from the highlands and Tharsis. 

Relief & elevation. Broad, low-lying plains a few kilometers below the areoid, floored by ridged plains and channel/fan deposits; smoothness increases toward central Chryse–Acidalia.

Geology & landforms. Chryse Planitia: circular lowland with wrinkle ridges and Hesperian–Amazonian plains; receives outflows from Tharsis and Valles Marineris. Acidalia Planitia: mounds aligned in fields (often interpreted as mud-volcano features) and polygonal trough patterns near the dichotomy boundary. Outflow channels: Kasei/Maja/Tiu/Simud/Ares deliver vast sediment packages; Pathfinder landed at Ares Vallis (19.3°N, 33.5°W). 

Surface texture. Extensive smooth plains with local armored surfaces, streamlined islands, and channel bars; dust sheets and dune patches in lows. 

Weather/temperature tendencies. As deep lowlands, Chryse–Acidalia experience higher ambient pressures than surrounding uplands; frequent dust hazes modulate light and visibility. (MOLA/pressure context + northern plains climatology.)

Notable observations. Viking 1 (22.5°N, 47.97°W) demonstrated volcanic–sedimentary plains at the landing site; Pathfinder at Ares Vallis sampled flood-emplaced materials and ventifacts.