Tag: iceland

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Snaefellsnes Peninsula – Iceland

Steingrimur Thorbjarnarson

The Snæfellsnes Peninsula is a particularly remarkable region of Iceland because it hosts three distinct volcanic systems aligned roughly east–west across the peninsula. Two of these systems have very similar names. The easternmost system is Ljósufjöll, and the central one is Lýsufjöll. Both names carry essentially the same meaning: “the light-coloured mountains.”

This name refers to the relatively silica-rich rock types found in these systems. Compared to many other volcanic areas in Iceland that are dominated by darker basaltic compositions, these systems contain a higher proportion of evolved, more silicate-rich rocks. The lighter coloration of the rhyolitic and dacitic components gives the mountain ranges their distinctive appearance and explains the origin of the names.

An additional noteworthy feature lies beneath the town of Stykkishólmur. The town receives geothermal hot water from a fracture zone whose orientation corresponds closely with predicted structural alignments derived from the convection rolls model of mantle flow. According to this interpretation, a deep-seated division line, representing a boundary between adjacent long convection rolls in the mantle, generated stress conditions favorable for fracture formation in the overlying crust. The present-day geothermal circulation would then be a surface expression of this deeper structural control.

At the same time, the surface morphology of the peninsula has been strongly modified by repeated glaciations. Glacial erosion has carved valleys and lineaments that follow a different dominant alignment. Interestingly, this second alignment also corresponds to another predicted set of division lines within the convection rolls model. In other words, both the geothermal fracture system and the glacially sculpted surface features appear to reflect deep structural patterns rooted in mantle convection dynamics.

Taken together, the volcanic distribution, geothermal fracture orientation, and glacial lineaments on the Snæfellsnes Peninsula may therefore represent multiple surface expressions of a deeper, organized mantle flow structure.

The town of Stykkishólmur:

Here it is on the map:

The town is heated with water from this fracture:

The surface is shaped according to another set of lines, also to be calculated:

On the westernmost tip of the Snæfellsnes Peninsula, Snæfellsjökull rises prominently above the surrounding landscape. This glacier-capped stratovolcano dominates the region both visually and geologically, forming a dramatic landmark at the edge of the Atlantic Ocean. Its symmetrical form and ice-covered summit make it one of Iceland’s most recognizable volcanoes.

Near its slopes once stood the home of Guðríður Þorbjarnardóttir, one of the most remarkable women of the Viking Age. Around the year 1000, she traveled with her husband to Vinland, where she lived for three years. During that time, she gave birth to her son, Snorri Þorfinnsson, who is considered the first European child born in the New World. Vinland is the old Icelandic name of the part of North America found south of Helluland (Baffinland) and Markland (Labrador), centuries before Columbus sailed over the Atlantic Ocean.

On the other side of the glacier, this painting shows Columbus in Iceland:

Behind them rises Snæfellsjökull, the glacier-capped volcano that inspired Journey to the Center of the Earth by Jules Verne. In Verne’s novel, the entrance to Earth’s interior is hidden within the crater of Snæfellsjökull, transforming this already dramatic volcano into a literary gateway to the planet’s deepest mysteries.

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From Iceland to Norway: The Recurring 30° Signature

Steingrimur Thorbjarnarson

The distance between central Iceland and the coastal regions of Norway corresponds to 30 degrees of longitude along the relevant parallels near 64°N. Within the framework of the mantle convection roll model, this spacing is consistent with a predicted division between adjacent lower-mantle flow rolls.

Interestingly, the Norwegian coastline closely follows the calculated lower-mantle division line. This correlation is significant, particularly because many major petroleum fields are located along the Norwegian continental margin. From a geological perspective, the precision of this 30° spacing is striking.

Moreover, the seismic distribution of Norway appears to reflect this structure, as earthquake activity is concentrated along this same zone.

A similar longitudinal distance appears elsewhere in the Atlantic system. At the equator, the distance between the Mid-Atlantic Ridge and the west coast of Africa is also approximately 30°. Furthermore, the Atlantic Ocean spans about 60° of longitude between the estuary of the Amazon River in South America and the African coast. The recurrence of these angular distances, 30° and 60°, suggests a possible large-scale structural regularity in mantle dynamics.

The Iceland–Greenland relationship presents a related but slightly more complex case. An additional rifting episode occurred between Baffin Island and Greenland during the opening of the Labrador Sea and Baffin Bay. Remarkably, the distance between the west coast of Greenland and central Iceland is also 30°. This may indicate that division lines between major convection rolls tend to align with continental margins, particularly at key latitudes such as the equator and around 64°N.

Another notable geometric relationship is that the Bering Strait lies 180° east (and west) of the Norwegian coast, placing it on the opposite side of the globe along a great-circle alignment. The Bering Strait is not found to be responsible for any rifting process, it just happens to be flooded, but according to the convection rolls model, a division below of the lower mantle, is found there!

Mainland of Eurasia 180 at 64N - 02

Elaboration on the Geodynamic Implications

Several implications follow these repeated 30° intervals:

1. Preferred Longitudinal Spacing of Convection Rolls

A 30° spacing corresponds to 12 divisions around the globe (360° / 30° = 12). This reflects a stable wavelength of large-scale lower-mantle convection rolls. Such rolls impose long-lived stress fields on the lithosphere, influencing rifting, margin formation, and sedimentary basin development.

2. Continental Margins as Surface Expressions of Mantle Boundaries

If lower-mantle division lines localize lithospheric weakness, continental breakup and passive margin formation may preferentially occur above them. This can help explain:

  • The Norwegian margin petroleum provinces
  • The Greenland–Baffin rift system
  • The equatorial South America (30°) – Atlantic Ocean (60°) – Africa (30° Great Rift Valley) – Indian Ocean (60°) – Indonesia (30°) – Pacific Ocean (150° Ring of Fire) symmetry.

3. Seismicity Concentration

The observation that Norwegian seismicity aligns with the inferred mantle boundary at the abyss strengthens the argument that deep mantle structures can influence intraplate stress fields.

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Explanation of Why Iceland’s Highest and Lowest Points Meet at the Volcano Öræfajökull and Jökulsárlón (the Glacier Lagoon)

Steingrimur Thorbjarnarson

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.

Drift vectors of Iceland

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The Golden Circle and West Iceland: Two Sides of the Same Mantle-Convection Polygon

Steingrimur Thorbjarnarson

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.

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The Skagafjörður Volcanic Zone: A Relic of Iceland’s Shifting Rift System

Steingrimur Thorbjarnarson

Around 3 million years ago, a volcanic zone developed in the Skagafjörður region, extending across what is now the Skagi Peninsula in northern Iceland. This area was part of the Neovolcanic Zone at the time — the active rift that carried most of Iceland’s volcanic and tectonic activity.

For roughly 2–2.5 million years, the Skagafjörður volcanic system produced extensive basaltic lava flows, which now blanket the Skagi Peninsula. These lava layers form a thick sequence of Pleistocene basalt plateaus, showing clear evidence of successive fissure eruptions and long-lived rift activity.

The Skagafjörður volcanic zone formed approximately 3° farther west, but at the same latitudes as the present-day Northern Volcanic Zone. This spatial relationship is not coincidental: it reflects the underlying mantle convection pattern. In Iceland’s mantle, long convection rolls extend roughly 1.5° in width from east to west. These rolls guide upwelling zones and determine where rifting and volcanism are concentrated at the surface.

Thus, both the Skagafjörður and Northern Volcanic Zones are expressions of the same large-scale convection pattern — successive manifestations of upwelling between the same pair of convection rolls, but active at different times as the spreading axis gradually shifted eastward.

Volcanic activity in Skagafjörður ceased less than 700,000 years ago, marking the end of its active phase. By then, the rift axis had shifted eastward and thereby replaced by the current Northern Volcanic Zone. During the active period of the Skagafjörður system, tectonic drift continued, resulting in approximately 10 km of crustal extension. This stretching contributed to the widening of Skagafjörður, later sculpted by glaciers into the broad fjord we see today.

The Skagi Peninsula, now far from any active volcanic centers, remains a silent geological record of this earlier rift episode — a remnant of the same convection-driven dynamics that continue to shape Iceland’s landscape today.

The two NS-axis of Iceland – old and new

Here you see the light blue colored area of Skagi, isolated from other volcanic areas.

https://www.langdale-associates.com/iceland_2017/prologue/geology_map.htm