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Antarctica displays several different levels of large-scale geometric organization. These should not be confused with one another, because they are based on different observations and have different degrees of certainty.

Article link (with inserted map): https://www.nature.com/articles/s41561-026-01991-6

Map base: https://www.sciencedirect.com/science/article/pii/S1674984722000775

At the most familiar level, the continental part of Antarctica is divided into East Antarctica and West Antarctica. East Antarctica consists largely of old Precambrian continental crust, whereas West Antarctica is much more tectonically fragmented and includes the West Antarctic Rift System. The Transantarctic Mountains form the most conspicuous boundary between these two major regions. This fundamental division has been recognized for many decades and is firmly established by geological and geophysical observations.

At another scale, when the entire Antarctic tectonic plate is considered, including its oceanic lithosphere, a broader geometric pattern becomes visible. In the Mantle Convection Roll model, the outline of the Antarctic Plate can be approximated by an elliptical form centred approximately on the South Pole. A major and a minor axis then divide this ellipse into four main sectors. The axes used in this comparison are approximately 70°22.5′E–109°37.5′W and 160°22.5′E–19°37.5′W, respectively.

A third and much more tentative possibility has now become particularly interesting. New geophysical results from East Antarctica may indicate that another level of organization exists: a division into sectors of approximately 60° around the South Pole.

This is not established. It is a geometric possibility suggested by comparison between the new observations and the larger Antarctic pattern. But the measurements are remarkable enough to make such a comparison worthwhile.

The East Antarctic Fan-Shaped Basin Province

In 2026, Armadillo et al. described what they call the East Antarctic Fan-Shaped Basin Province (EAFBP). Using improved subglacial topographic data together with seismic, gravity and magnetic information, they identified 30 major basins beneath a very large part of the East Antarctic Ice Sheet. Many are approximately V-shaped and elongated radially towards the interior of Antarctica. Collectively, the basins form a huge fan-like structure extending roughly from Prydz Bay at 70°E to the Transantarctic Mountains at about 160°E.

This is not merely a visual impression from a map. The authors fitted 60 great circles to the longitudinal edges of the basins and calculated more than one thousand intersections. From these they obtained a best-fitting Euler pole at 86.4°S, 129.9°E.

This point is only about 3.6° of latitude, or roughly 400 km, from the geographic South Pole. The fan also has a well-defined axis close to the 130°E meridian, passing through the Belgica Subglacial Highlands. The authors call this the Belgica Bisector. The observed basin system is divided by this line into a sinistral sector to the west and a dextral sector to the east.

There is additional evidence that the geometry penetrates deeply into the lithosphere. Models based on seismic and gravity information show reduced crustal thickness beneath the major basins, while seismic tomography identifies low-velocity anomalies beneath the Wilkes and Aurora basins at upper-mantle depths. Thus, the fan-shaped pattern is not simply a feature produced by glacial erosion at the surface.

Perhaps even more strikingly, the authors identify two approximately circular transverse shear belts. Independent fitting gives Euler poles at 84.2°S, 130.8°E and 83.1°S, 129.5°E.

Thus three separately calculated geometric poles cluster within a relatively small region close to the South Pole and close to the same meridian: 86.4°S, 129.9°E, 84.2°S, 130.8°E, and 83.1°S, 129.5°E.

This repeated convergence towards the polar region is an important observational result, regardless of how its cause is ultimately interpreted.

Rotational extension — observation or explanation?

Armadillo et al. interpret the structure as the product of distributed intraplate rotational extension. In their model, the crust opened rather like a handheld fan around an Euler pole close to the South Pole. The Aurora and Wilkes basins developed on opposite sides of the Belgica Bisector, and displacement increased away from the pivot. The geometry certainly supports a rotational description.

However, there is an important distinction between describing the resulting deformation and identifying the deeper force that produced it. In the interpretation considered here, rotational extension may be a secondary kinematic effect rather than the primary geodynamic cause.

The proximity of the calculated Euler pole to the geographic South Pole is therefore particularly important. It does not, by itself, prove that Earth’s rotation caused the deformation. An Euler pole is fundamentally a geometric description of rotational motion, and many plate motions have Euler poles unrelated to geographic poles. Nevertheless, when a continental-scale system of radially arranged structures produces several independently calculated deformation poles close to the geographic pole, the relationship deserves attention—particularly in a model in which mantle convection itself is organized by planetary rotation.

The role of Earth’s rotation

Earth’s rotation alone cannot provide a satisfactory direct mechanical explanation for opening major crustal basins hundreds or thousands of kilometres long. The stresses required must ultimately be transmitted through the lithosphere from processes capable of doing substantial tectonic work.

In the Mantle Convection Roll model, the connection is indirect but mechanical:

Earth’s rotation → organization of mantle convection → systematic mantle-flow stresses → deformation of the lithosphere.

The rotation of the Earth organizes the convection system. The mantle flow then supplies the forces acting on the overlying lithosphere. From this perspective, a tectonic pattern centred close to the geographic pole would not result simply from a vague “rotational force”. It would reflect the geometry of a mantle-flow system whose organization is itself controlled by rotation.

The new Antarctic measurements provide evidence for the geometry of deformation. They do not establish the Mantle Convection Roll interpretation. But they provide a new and unusually clear geometric pattern against which that model can be tested.

Could Antarctica contain six alternating 60° sectors?

The mapped EAFBP extends approximately from 70°E → 160°E.

Its Belgica dividing line lies near 130°E. Consequently, the observed western part extends approximately 70°E → 130°E = 60°.

The mapped eastern part extends only 130°E → 160°E = 30°.

But 160°E corresponds approximately to the Transantarctic Mountains and the transition into West Antarctica. The quality and nature of the available observations change substantially beyond this region. The absence of a mapped continuation therefore does not necessarily demonstrate that deformation stopped there. Indeed, the West Antarctic Rift System itself records enormous crustal extension and a long history of tectonic reorganization.

This permits an alternative geometric question. What if 130°E represents the boundary of a 60° sector, rather than the centre of the complete Antarctic deformation system? A hypothetical dextral sector could then extend approximately 130°E → 170°W, with its centre at 160°E.

The next 60° sector would extend 170°W → 110°W, and could potentially display predominantly sinistral characteristics.

If this alternating pattern continued around the pole, the full 360° circumference would consist of six sectors:

sinistral – dextral – sinistral – dextral – sinistral – dextral, each occupying approximately 60°.

This is presently only a hypothesis. The available geophysical mapping is far too incomplete to claim that such a sixfold structure has been demonstrated. But there is an interesting numerical consequence. A system beginning with a sector boundary near 130°E generates boundaries approximately at:

10°E – 70°E – 130°E – 170°W – 110°W – 50°W.

Its sector centres would lie at:

40°E – 100°E – 160°E – 140°W – 80°W – 20°W.

This has an unexpected relationship with the independently derived elliptical geometry of the Antarctic Plate.

The proposed major elliptical axis, at approximately 70°22.5′E ↔ 109°37.5′W,

lies almost exactly on two opposite boundaries of such a 60° system.

The proposed minor elliptical axis, at approximately 160°22.5′E ↔ 19°37.5′W, instead lies almost exactly through the centres of two opposite sectors. Thus the possible sixfold division would not replace the fourfold elliptical division. The two geometries could be superimposed.

One describes the principal axes and quadrants of the Antarctic Plate, and the other might describe an alternating pattern of deformation around the pole.

Antarctica therefore shows three different levels of organization

The distinction can be summarized conceptually as follows:

1. Twofold division — continental geology

East Antarctica and West Antarctica represent the first-order geological division of the Antarctic continent.

2. Fourfold division — Antarctic Plate geometry

When the oceanic part of the tectonic plate is included, the larger outline can be examined as an approximately elliptical, pole-centred structure divided into four quadrants by its major and minor axes.

3. Possible sixfold division — internal deformation

The newly identified fan-shaped basin system raises the possibility that deformation around the pole may additionally be organized into approximately 60° sectors, possibly with alternating sinistral and dextral characteristics.

Only the first of these is conventional tectonic classification. The second is a geometric observation made in the Mantle Convection Roll analysis. The third is presently a hypothesis arising from comparison with the newly published EAFBP results.

It is important not to present the sixfold division as established geology.

What is established by the new measurements is already remarkable: a semi-continental-sized system of subglacial basins is arranged radially around a focal region very close to the South Pole; two major basins are approximately symmetrically arranged about a ~130°E bisector; the crust is thinned beneath major parts of the system; and three independently calculated deformation poles cluster close to the South Pole.

A pole-centred continent

This is the broader significance of the observations.

Antarctica contains geological structures whose large-scale geometry is demonstrably organized with respect to a region close to the geographic pole.

The authors of the EAFBP study explain this through rotational extension around an Euler pole. That is a legitimate kinematic interpretation of their observations.

The Mantle Convection Roll model asks a different question: Why should a continental-scale deformation system have a rotational centre so close to the geographic South Pole in the first place?

Within this model, the answer would not be that Earth’s rotation directly tears the crust apart. Rather, Earth’s rotation organizes the underlying mantle-convection system. Different components of that system generate different directions and strengths of mantle flow, and those flows provide the forces required for extension, shear, compression and eventual continental separation.

This also provides a possible context for the fragmentation of Gondwana around Antarctica. Different continental fragments separated from different parts of the Antarctic margin at different times. Australia, Zealandia, India, Africa and South America did not detach simultaneously, and their individual histories must be treated separately. Nevertheless, it remains possible that pre-existing, pole-centred mantle-flow geometry influenced where the lithosphere was stretched, where major weaknesses developed, and how those weaknesses were repeatedly reactivated.

Interestingly, Armadillo et al. themselves propose that the northern margin of the fan-shaped province created or exploited a lithospheric weakness that later influenced the separation of Australia from Antarctica and the geometry of the conjugate continental margins.

The difference lies mainly in the proposed primary cause.

Their model begins with rotational extension of the Antarctic lithosphere.

The Mantle Convection Roll interpretation would place another level beneath it:

planetary rotation → organized mantle convection → lithospheric stress field → rotational extension and other tectonic responses.

The fan-shaped opening would therefore be an expression of the system rather than its fundamental cause. For that reason, the new East Antarctic results are particularly useful. They do not need to have been discovered from the Mantle Convection Roll model, nor do they need to have been measured specifically to test it. Quite the opposite: their value lies in being independent geophysical observations.

The structures were mapped from subglacial topography, seismic data, gravity and magnetic measurements. Their geometry was calculated independently. Only afterwards can these observations be compared with the predicted or previously identified geometry of a pole-centred mantle-convection system.

That is precisely the kind of comparison on which the model can be tested.

Reference: Armadillo, E. et al. (2026), A fan-shaped subglacial basin province in East Antarctica formed by rotational extension, Nature Geoscience 19, 715–722, doi:10.1038/s41561-026-01991-6.

The tectonic settings of the San Andreas Fault in California and the Alpine Fault in New Zealand are comparable in several respects. When the elliptical geometry of the Ring of Fire is constructed, the two faults appear approximately opposite one another on either side of the Pacific, with their positions related to the minor axis of the ellipse. A closer comparison, however, reveals several additional geometric relationships.

As shown on the maps below, the central parts of both faults coincide with major lower-mantle boundaries predicted by the Mantle Convection Roll system. In the case of the San Andreas Fault, the inner boundary of the Ring of Fire ellipse also closely coincides with the creeping section of the fault. The San Andreas Fault therefore provides one of the clearest examples of the proposed geometric position of the inner boundary of the Ring of Fire. The midpoint of the creeping section, at approximately 36.38°N, 120.98°W, lies on one of the principal boundaries of the lower-mantle roll system.

The northwestern continuation of the San Andreas system is also noteworthy, as it trends toward the southern end of the Juan de Fuca Ridge. From the central part of the San Andreas Fault, a line can then be drawn toward the Yellowstone Caldera. Yellowstone also lies on a north–south axis that, in the geometry developed here, represents a continuation from the major axis of the Antarctic ellipse. This N–S axis also corresponds to a central axis within the Mantle Convection Roll system.

A closely comparable arrangement is found at the Alpine Fault. The central part of the fault lies on a principal lower-mantle boundary, in much the same way as the central part of the San Andreas Fault. The orientation of the Alpine Fault is also approximately parallel to the line connecting the San Andreas Fault with Yellowstone. A second parallel line can therefore be drawn from the central Alpine Fault toward an N–S axis extending from the minor axis of the Antarctic ellipse. This produces a geometric counterpart to the San Andreas–Yellowstone relationship.

The intersection between this N–S continuation of the Antarctic minor axis and the minor axis of the Ring of Fire ellipse defines, in this construction, the outer boundary of the Ring of Fire ellipse. The distance from the Alpine Fault to this intersection is shorter than the corresponding San Andreas–Yellowstone distance. This difference is related to the fact that the four N–S axes used in this geometry are systematically displaced approximately 1.5° eastward from the corresponding system centres of the Mantle Convection Roll model.

The distance between the San Andreas Fault and Yellowstone corresponds to one complete lower-mantle convection-roll interval, equivalent to ten smaller roll intervals. In the Alpine Fault case, the corresponding distance amounts to eight such intervals. According to this geometry, the inner and outer boundaries of the Ring of Fire are therefore not perfectly symmetrical.

Zooming in: The comparison consequently reveals a considerable number of mutually consistent geometric relationships between the San Andreas and Alpine faults: their opposing positions relative to the minor axis of the Ring of Fire, the location of their central sections on major lower-mantle boundaries, the parallel orientation of the faults and their associated connecting lines, and the regular spacing produced by the Mantle Convection Roll system. The following maps are presented to illustrate these relationships and allow the two regions to be compared directly.

Hvað

According to the USGS, six major geyser regions can be identified in the world: Iceland, Yellowstone in the United States, the Valley of Geysers in Kamchatka, the Taupō–Rotorua region of New Zealand, El Tatio in Chile, and Lake Bogoria in Kenya.

https://www.usgs.gov/media/images/map-showing-locations-major-natural-thermal-geyser-fields

For first comparison:

Geysers are rare because their formation requires a particular combination of geothermal heat, groundwater, permeable fractures, and a confined underground plumbing system in which water can become superheated before erupting at the surface.

According to the geometric interpretation presented here, the locations of all six major geyser regions can be related to prominent axes, ellipses, and major tectonic divisions shown on the map below.

Iceland, Yellowstone, and Kamchatka all lie in direct continuation of the principal axes of the Antarctic ellipse. New Zealand is located near the intersection of the minor axis of the Ring of Fire and its inner elliptical form. Kenya is associated with the Great Rift Valley of Africa, close to the Equator, while El Tatio in Chile lies on the outer rim of the elliptical form of the Ring of Fire. Thus, all six of the world’s most prominent geyser regions can be related to the principal geometric features described here.

In the case of Iceland, the accuracy level is tremendous:

1. Iceland – Geysir and Strokkur

Iceland contains one of the classic geyser regions of the world. The best-known examples are Geysir and Strokkur in Haukadalur. Strokkur erupts frequently, while the activity of Geysir has varied considerably through historical time.

The Icelandic geothermal systems are associated with intense volcanism, abundant groundwater, fractured volcanic rocks, and a high geothermal gradient. Water can circulate downward through fractures, become heated at depth, and rise again. In a geyser, restrictions within the underground conduit allow pressure to build until part of the water suddenly flashes into steam, producing an eruption.

Within the geometric framework shown here, Iceland lies in the direct continuation of the minor axis of the Antarctic ellipse. The continuation of this axis extends northward through the Atlantic region towards Iceland.

2. Valley of Geysers, Kamchatka

The Valley of Geysers in Kamchatka, Russia, is one of the largest and most concentrated natural geyser fields in the world. It contains numerous geysers, hot springs, steam vents, and other hydrothermal features within a highly active volcanic environment.

Kamchatka is located along a major subduction zone, where the Pacific Plate descends beneath the region. This produces extensive volcanism and provides the heat necessary for powerful hydrothermal systems. Groundwater circulates through fractured volcanic rocks and is heated at depth, allowing geysers to develop where the underground plumbing has the appropriate geometry.

Geometrically, the Valley of Geysers is particularly significant because Kamchatka lies in the direct continuation of the minor axis of the Antarctic ellipse on the opposite side of the Earth from Iceland. Thus, Iceland and Kamchatka are associated with opposite extensions of the same principal axis.

3. Yellowstone, United States

Yellowstone National Park contains the greatest concentration of active geysers in the world. Famous examples include Old Faithful, Grand Geyser, Castle Geyser, Beehive Geyser, and Steamboat Geyser.

The Yellowstone hydrothermal system is powered by an exceptionally large volcanic and geothermal system beneath the Yellowstone Plateau. Rainwater and snowmelt penetrate deeply into fractured rocks, where they are heated and subsequently rise through complex networks of fractures and conduits. In geysers such as Old Faithful, the shape of the underground reservoir and conduit permits pressure to accumulate and produces repeated eruptions.

Within the geometry examined here, Yellowstone lies in the direct continuation of the major axis of the Antarctic ellipse. This places one of the world’s most important geothermal and geyser regions along another principal axis defined by the Antarctic geometry.

4. New Zealand – Taupō and Rotorua

New Zealand contains several major geothermal areas, particularly within the Taupō Volcanic Zone, including the Rotorua and Whakarewarewa geothermal fields. Pohutu Geyser is one of the best-known active geysers in the region.

The Taupō Volcanic Zone is characterized by active volcanism, large caldera systems, abundant fractures, and powerful hydrothermal circulation. Hot groundwater rises through volcanic rocks and produces geysers, hot springs, mud pools, and steam vents. Some historic geysers in New Zealand have changed or disappeared as a result of natural changes and human use of geothermal groundwater.

The position of the New Zealand geyser region is especially noteworthy in the present model. It lies on the minor axis of the Ring of Fire, close to the point where this axis crosses the inner ellipse of the Ring of Fire. The geyser region therefore occurs at an important geometric intersection within the circum-Pacific system.

5. El Tatio, Chile

El Tatio, in the high Andes of northern Chile, is one of the world’s major geyser fields. It contains numerous geysers, hot springs, fumaroles, and steaming geothermal pools. Individual eruptions are generally smaller than those of the largest geysers in Yellowstone or Iceland, but the number and concentration of geothermal features make El Tatio exceptional.

The heat source is related to Andean volcanism above the subduction zone along the western margin of South America. Water circulating through fractured rocks is heated by the volcanic geothermal system before returning to the surface.

In the geometry presented here, the Chilean geyser region lies on the outer margin of the Ring of Fire. Its position therefore corresponds directly with the major circum-Pacific tectonic and volcanic boundary.

6. Lake Bogoria, Kenya

The geothermal region around Lake Bogoria in Kenya contains hot springs, steam vents, and numerous small geysers. Although many of these geysers are considerably smaller than Geysir, Strokkur, or the major Yellowstone geysers, they operate according to the same basic hydrothermal principles.

Lake Bogoria lies within the East African Rift System, where the continental lithosphere is being stretched and fractured. This tectonic setting allows heat and fluids to rise relatively close to the surface and produces extensive volcanic and geothermal activity.

Its geographic position is particularly important in this comparison. The Lake Bogoria geyser field lies very close to the Equator and directly within the Great Rift Valley. It therefore represents the sixth major geyser region at the intersection of a major continental rift system with the equatorial zone.

Geometric Relationship of the Six Geyser Regions

The six major geyser regions occur in very different geological environments. Iceland is associated with an oceanic spreading system, Kamchatka and Chile with subduction-related volcanism, New Zealand with an active volcanic and plate-boundary region, Yellowstone with a major continental volcanic system, and Kenya with continental rifting. Nevertheless, all require the same fundamental conditions for geyser formation: a strong heat source, groundwater, fractured and permeable rocks, and an underground conduit system capable of retaining pressure.

When their geographic positions are compared with the geometry shown on the map, an additional pattern appears:

• Iceland lies on the northern continuation of the minor axis of the Antarctic ellipse.
• Kamchatka lies on the continuation of the same minor axis on the opposite side.
• Yellowstone lies in the continuation of the major axis of the Antarctic ellipse.
• New Zealand lies on the minor axis of the Ring of Fire, where it intersects the inner Ring of Fire ellipse.
• El Tatio in Chile lies along the outer margin of the Ring of Fire.
• Lake Bogoria in Kenya lies at the Equator within the Great Rift Valley.

All six locations are marked on the map below. The comparison is therefore not based only on the presence of geothermal activity. It shows that the world’s principal geyser regions occupy specific positions in relation to the major geometric and tectonic structures considered in this study.

The geometric relationships between the major geyser regions can be divided into several partly overlapping groups. It is important not to treat all of them as the same type of correspondence, because some are close point-to-line matches, while others involve larger tectonic or volcanic zones.

Iceland, the Valley of Geysers in Kamchatka, and Yellowstone form one group related to the geometric framework derived from the Antarctic Plate and the equatorial divisions. Geysir in Iceland is particularly interesting because it is not located directly on the principal axis at 19°37.5′W, but close to a subdivision line half a 1.5° interval farther west. This theoretical line lies at 20°22.5′W, while Geysir is at about 20°18′W. The difference is only about 0.075°, corresponding to roughly 4 km at this latitude. Thus, Geysir can be regarded as a close point-to-line correspondence within the subdivision system rather than as a direct match with the principal axis itself.

The Valley of Geysers and Yellowstone are also related to the Antarctic-derived geometry, but they have an additional and independent-looking relationship with the geometry of the Pacific Ring of Fire. In this second system, four major geyser regions occupy characteristic positions along the inner and outer margins of the Ring of Fire.

The Valley of Geysers in Kamchatka lies along the inner boundary of the Ring of Fire geometry. New Zealand, another of the world’s major geyser regions, is likewise associated with the inner boundary. On the opposite side of the geometric pattern, Yellowstone lies close to the outer boundary, while El Tatio in Chile is also located along the outer boundary.

This produces a striking two-by-two arrangement:

	Inner boundary	Outer boundary
Northern sector	Valley of Geysers, Kamchatka	Yellowstone
Southern sector	New Zealand	El Tatio, Chile

A further relationship is superimposed on this arrangement. New Zealand and Yellowstone are positioned in relation to the minor axis of the Ring of Fire ellipse. They are therefore not merely two geyser regions situated on different margins of the same geometric form; they also define, or lie close to, one of its principal axes.

Yellowstone and the Valley of Geysers are consequently of particular interest because they belong to both geometric groups. The Valley of Geysers is related both to the Antarctic-derived framework and to the inner boundary of the Ring of Fire. Yellowstone is related to the Antarctic framework, the outer boundary of the Ring of Fire, and the minor-axis geometry of the Ring of Fire. The recurrence of the same exceptional geothermal regions in more than one independently defined geometric relationship is more significant than a simple comparison of individual coordinates.

Kenya provides a different type of correspondence. Lake Bogoria lies very close to the equator within the Kenya Rift, which forms part of the eastern branch of the East African Rift System. The relevant geometric division also passes through the eastern rift system. Here the correspondence should therefore not be described as a geyser lying exactly on a single line. Rather, the subdivision line corresponds with a major tectonic zone, and the geyser field occurs within that same zone.

Iceland has a related connection with the equatorial subdivision system. Its major geothermal field at Geysir lies close to a longitude derived from one of the equatorial division points. In this sense, both Iceland and Kenya illustrate how the equatorial division system may correspond with major rifting and geothermal environments, although the geological expression is very different in the two regions.

These relationships can therefore be summarized as three overlapping geometric patterns:

1. Antarctic and equatorial geometry: Iceland – Valley of Geysers – Yellowstone, with Kenya providing an additional connection through the equatorial division and the East African Rift.
2. Inner and outer Ring of Fire geometry: Valley of Geysers – New Zealand on the inner boundary; Yellowstone – El Tatio on the outer boundary.
3. Minor axis of the Ring of Fire: New Zealand – Yellowstone.

The comparison is complicated by the fact that geyser regions differ greatly in size and geological setting. Geysir in Iceland can be compared quite precisely with a longitude, whereas Yellowstone is a very large volcanic and hydrothermal system, and Lake Bogoria is best understood in relation to an entire rift zone. For this reason, the significance of the pattern should not be judged solely by measuring the distance of each geyser from a single theoretical line. The more relevant question is whether the world’s most prominent geyser regions repeatedly occupy characteristic positions within a geometric framework that was defined independently of the geysers themselves.