There are many ways in which Iceland can be meaningfully compared with the convection-rolls model of mantle flow. When viewed from a holistic, bird’s-eye perspective, the combined pattern of the continental shelf, mid-ocean ridges, and the alignment of Iceland’s stratovolcanoes begins to tell a coherent geological story.
To make full sense of this, however, it is essential to understand both the location and the function of the major convection rolls situated beneath Iceland.
Once the geometry of these convection rolls is recognized, the division lines between them clearly mark the boundary limits of Iceland’s volcanic zones.
Numerous specific details illustrate this correspondence—for example, the distribution of Iceland’s primary geothermal areas aligns closely with the convection roll that extends from the Reykjanes Ridge beneath the island.
With this convection-roll framework in place, further analysis becomes possible, such as subdividing the volcanic zones into their natural segments and comparing the intensity and style of activity within each one.
The tectonic drift vectors across Iceland can also be compared directly with the grid formed by the convection-roll boundaries. This allows an accurate, physically meaningful line to be drawn representing the division between the North American and Eurasian plates.
In turn, Iceland’s smaller peripheral volcanic zones can be examined in this context.
These zones tend to occupy the regions between the edges of adjacent convection-roll polygons. In fact, virtually every detail of Iceland’s tectonics, geothermal distribution, and volcanic structure can be actively compared—and consistently correlated—with this convection-roll system. This approach provides a unified model that connects deep-mantle dynamics with the observable geological features on the surface.
Many of the famous volcanic and geothermal areas in Iceland are distributed in a very regular pattern:
When we trace three specific latitudinal bands across Iceland, a striking regularity emerges in the distribution of volcanic and geothermal areas. These zones appear to align with key boundaries in Iceland’s underlying mantle-convection structure.
1. The ~64°48′N Parallel Along approximately 64°48′N, several well-known volcanic and geothermal sites fall in a remarkably linear arrangement. Snæfellsjökull (64°48′32″N) lies on this line, and further east we encounter Reykholtsdalur, Hveravellir, the East Volcanic zone – Mid Volcanic Belt (EVZ–MVB) division point, Kverkfjöll, and Snæfell. The fact that such major and geographically separated systems cluster around the same latitude suggests that their positions are not random; they coincide with an underlying structural feature in the mantle.
2. The ~64°19′N Parallel Geysir is located at 64°18′49″N, and 3° of longitude to the east lies Grímsvötn, one of Iceland’s most active volcanic centers. This west–east correspondence hints that these two sites sit along the same deep-seated mantle boundary, where material upwelling or shear occurs as adjacent convection rolls interact.
3. The ~64°00′N Parallel A third set of volcanic features—Hveragerði, Hekla, Laki, and Öræfajökull—also display a regular spacing. Each lies approximately 1.5° apart along the 64th parallel. These evenly spaced intervals are consistent with boundary intersections between mantle convection rolls. cells.
How These Parallels Fit Together
When plotted on a map, these three latitudinal bands exhibit a coherent geometric relationship. Rather than being isolated curiosities, they form a patterned framework that mirrors the predicted arrangement of convection rolls of the upper mantle. In the model, Iceland sits above the junction of several long, ribbon-like convection structures that rise and sink in a repeating pattern. Where roll boundaries intersect, and special structures or divisions are found on the surface, it can be regarded as a theoretical explanation of the relevant geological circumstances.
The Icelandic data align with this idea:
Volcanoes and geothermal fields cluster where convection-roll boundaries intersect.
Spacing is regular, matching the predicted periodicity of mantle-flow structures.
Parallel latitudinal bands correspond to horizontal divisions between roll layers, while the longitudes match the vertical shear boundaries between adjacent rolls.
Broader Significance
These Icelandic examples support the broader global pattern: volcanic, seismic, and geothermal activity frequently coincides with the geometry of the Earth’s internal convection structure. Iceland—sitting atop a spreading ridge and a major upwelling—is particularly sensitive to the arrangement of these convection rolls, making it an ideal natural laboratory. The observed regularities reinforce the hypothesis that the distribution of volcanic centers is controlled not only by shallow crustal processes or isolated mantle plumes but also by the deeper, long-wavelength organization of mantle flow.
On the map, a question mark has been added, namely at the Snæfellsnes Peninsula, where one spot seems to be missing within an otherwise regular row of active sites. What does that mean?
The location of the Icelandic Geysir is above the lower mantle division lines, as seen below:
The location of the Geysir geothermal area in Iceland
Looking at the location in more detail:
A picture of the area can then be examined:
The Geysir geothermal area can be interpreted in a way that aligns naturally with the large-scale convection-roll model. The key is understanding how the regional structural geometry, the local fracture network, and the three-dimensional vapour reservoir interact. The area lies above two NW–SE-aligned division lines, which in the model represent boundaries between adjacent mantle-flow rolls. Such deep division lines tend to produce changes in the crustal stress field, zones of enhanced fracturing, and focused pathways for magmatic and hydrothermal fluids. It is therefore not surprising that the surface geothermal activity in Haukadalur is concentrated precisely where these boundaries intersect the crust.
These NW–SE structures meet and interfere with the dominant NE–SW trend of the West Volcanic Zone. The WVZ imposes the main tectonic and volcanic orientation in this part of Iceland, and when the two systems interact—one NE–SW, the other NW–SE—the result is a structurally complex zone with increased fracture permeability. Where these deep-rooted structural trends overlap, hydrothermal fluids can move more easily, leading to the clustering of geysers, steaming ground, and other geothermal features that characterise the Geysir field.
Recent geophysical imaging supports this interpretation by revealing that the vapour-dominated reservoir beneath the Geysir area stretches NW–SE. This alignment is significant: it matches the orientation of the proposed deep division lines and also cuts across the local anomaly long thought to reflect a fault or fracture connecting Geysir and Strokkur. Instead of a simple linear fault feeding the two geysers, the more plausible interpretation emerging from these observations is that the NW–SE vapour reservoir acts as the primary geothermal engine, while the Geysir–Strokkur line functions as a permeability pathway for warm water into this larger reservoir.
Viewed through the lens of the convection-roll model, the Geysir system becomes a clear example of how deep mantle-flow structures can influence surface geology. The NW–SE reservoir corresponds to a convection-roll division line, while the NE–SW orientation of the West Volcanic Zone reflects the regional upwelling limb of the roll, parallel to the main division lines, as shown on the maps. The interaction of these two trends produces the fracture architecture necessary to create one of Iceland’s most iconic geothermal systems. Rather than being controlled primarily by a local fault between Geysir and Strokkur, the system appears to be driven by the intersection of broader structural patterns inherited from deep mantle dynamics.
More about the vapour reservoir of the Geysir area:
Lupi, M., Collignon, M., Fischanger, F., Carrier, A., Trippanera, D., & Pioli, L. (2022). Geysers, boiling groundwater and tectonics: The 3D subsurface resistive structure of the Haukadalur hydrothermal field, Iceland. Journal of Geophysical Research: Solid Earth, 127, e2022JB024040. https://doi. org/10.1029/2022JB024040
Iceland’s highest mountain, Öræfajökull at 2110 meters, and its deepest lake, Jökulsárlón reaching 284 meters, sit side by side on the island’s southeastern margin. Their striking proximity reflects more than coincidence: it reveals the intersection of several major geological boundaries that meet precisely at this location. The key to understanding this lies in two geographic lines—64°N and 16°40’30”W—which together frame a tectonic corner of Iceland.
Öræfajökull and Fjallsárlón
The 64th parallel is an important structural boundary across Iceland. North of this line, the East Volcanic Zone is divergent, but south of 64°N the South Iceland Volcanic Belt is not. The South Iceland Seismic Zone is also found on on 64°N. This shift happens along the 64°N line, and Öræfajökull lies exactly upon this transition.
The meridian of 16°40’30”W forms another significant axis. This longitude aligns with the central line of the North Volcanic Zone farther north. When extended southward, this same line passes directly through Öræfajökull. In other words, the volcano sits on a southern continuation of one of Iceland’s major volcanic and tectonic axes, even though it lies east of the island’s main rift zones and firmly on the Eurasian Plate. Its position makes it a tectonic outlier—disconnected from the active rifts.
The relationship between Öræfajökull and the volcanic systems to the north further reveals the underlying structure. At the northern edge of Vatnajökull, the volcano Kverkfjöll stands at the southern end of the North Volcanic Zone, positioned at what can be seen as the northern corner of a polygon, as seen on the map. Öræfajökull sits directly south of Kverkfjöll along the same north–south axis, forming the southern corner of that same convection polygon.
At the 16°40’30”W line, the drift vectors diverge in different directions, and near 64°N, the vectors also change directions, from NE to NW. Where these shifting vectors meet, the crust experiences a twisting or hinging effect. Öræfajökull is located precisely at this corner where drift vectors split and rotate relative to each other.
This combination of structural transitions produces the unusual pairing of Iceland’s highest and lowest points. At Öræfajökull, all the division lines between convecton rolls are concentrated at one spot, and by the resistance of crustal blocks caught at the hinge of changing stress fields. Just a short distance away, the basin that now holds Jökulsárlón lies in a zone of subtle tectonic sag created by that same hinge. As the Breiðamerkurjökull glacier retreated, it carved this weakened zone even deeper, creating a basin that today reaches far below sea level. Thus, uplift and subsidence—opposing expressions of the same tectonic corner—appear literally side by side.
Öræfajökull, one of Iceland’s most powerful stratovolcanoes, and Jökulsárlón, carved into a structurally lowered basin at the foot of a retreating glacier, together mark a location where Iceland’s tectonics, mantle flow, and glacial history intersect. Their juxtaposition encapsulates the geological complexity of southeast Iceland: a place where the island’s major structural lines cross, where mantle convection shifts direction, and where the twisting of drift vectors produces both the highest land and the deepest lake in a single, dramatic landscape.
Visitors often experience Iceland’s geothermal wonders as isolated attractions—Geysir erupting in the south, hot springs boiling at Deildartunguhver in the west, rifting on display at Þingvellir. But when viewed through the lens of long-roll mantle convection, these sites reveal a striking order. They are not randomly scattered. Instead, they follow the geometry of a single, large-scale convection-roll polygon whose division lines extend from the Reykjanes Ridge deep into Iceland’s interior.
The Golden Circle occupies the southeastern side of this polygon, while the scenic geothermal and volcanic features of West Iceland mark the northwestern side. Together, they form a coherent and predictable system—one that becomes unmistakable once the underlying structure is recognized.
An overview:
Main Tourist Sites of Golden Circle and Saga Circle
For more detailed view:
The main tourist attractions near Reykjavík
The Southeastern Side: Golden Circle Precision
Þingvellir
Þingvellir sits near the center of the polygon, directly on its north–south axis. Here, equal pulling forces from both sides create the famous rift valley. Its placement is a textbook example of where the interior of a convection polygon should produce surface extension.
Hveragerði
Hveragerði offers one of Iceland’s cleanest demonstrations of deep-mantle structure expressed at the surface. The town lies exactly at the intersection of major mantle division lines, which explains the intensity and concentration of geothermal activity. It is a surface hotspot perfectly predicted by the geometry below.
Laugarvatn
Laugarvatn also aligns with exceptional accuracy. The geothermal area sits on two upper-level down-welling lines and lies directly above a major lower-mantle division boundary. Few places illustrate the coupling of shallow and deep mantle dynamics as clearly as Laugarvatn.
Geysir
Geysir rests directly on the down-welling line that extends northwest from Hekla. It also lies just southeast of the structural intersection that defines the north corner of the polygon’s southeastern side. This convergence of trends helps explain why the geothermal field is so active and persistent.
Gullfoss
The gorge of Gullfoss aligns with the same down-welling division pattern that links Hekla, Geysir, and the West Iceland features. The waterfall marks the upper end of a gorge whose orientation is controlled by the polygon’s structural lines.
These Golden Circle sites collectively trace the southeastern edge of the polygon with remarkable precision—far too precise to be coincidental.
The Northwestern Side: West Iceland’s Mirror Image
The same polygon continues seamlessly northwest, and the geothermal and volcanic features there align with the same degree of accuracy.
Reykholt
Reykholt lies on a major upwelling line extending from the Reykjanes Ridge. This upwelling brings heat toward the surface, establishing Reykholt as a thermal center on the polygon’s NW side.
Deildartunguhver
Iceland’s most powerful hot spring sits on the calculated continuation of the main part of the Reykjanes Ridge, and exactly on the east–west axis that cuts through the Reykholtsdalur area—a key boundary separating upwelling and down-welling segments. Its location makes complete structural sense when placed on the polygon map.
Hraunfossar & Barnafoss
These hydrological features lie on the other upwelling line from the Reykjanes Ridge and near the east corner of the Reykholtsdalur mini-polygon. The unusual phenomenon of water emerging directly from lava fields reflects this deeper structural positioning.
West Iceland’s features are therefore not separate anomalies—they are the northwestern continuation of the same convection-roll polygon that shapes the Golden Circle.
A Unified Geological Framework
When viewed together, the Golden Circle and West Iceland’s geothermal fields reveal a single, coherent pattern. They form opposite sides of the same polygon, shaped by long-roll mantle convection. Each site—Hveragerði, Laugarvatn, Geysir, Reykholt, Deildartunguhver, Hraunfossar—sits exactly where the division lines predict, demonstrating the extraordinary consistency of this framework.
Iceland’s most famous natural attractions are not isolated surface features. They are windows into the geometry of the deep Earth.
Magic Magma 