Author: Steingrimur Thorbjarnarson

The Convection Cell Model can help us to understand our surroundings better. Let us have a look at California on a GIS map base.

The main fault is located within a polygon close to the main division line of lower layer convection cells under the Rocky Mountains.

The polygon is here shown on a Google map. The symmetry causes an EW tectonic axis to form within the ductile part of the tectonic plate.

The main convection roll and the EW-axis compete for ruling the tectonic alignment, resulting in a ‘draw’ due to the balanced ductility level presumed to prevail below the brittle crust. The main topographic alignment becomes half the angle between them, shown with the red line.

That red line, forming the ‘1/2 angle’ compared with the EW axis is here called α:

α = (arc tan {[(35.34² – (ϕ – 32)²) ^0.5  / (ϕ – 32)](1/cos ϕ)})/2

where ϕ=39, so α=40.5°

The deviation from north at that latitude then becomes 90-40.5=49.5 or N49° 30’W.

With this knowledge at hand, analyzes of tension building up in the area becomes easier.

We are so lucky that we have land in the southern hemisphere at the same latitude as Iceland. It is known as the Antarctic Peninsula. We can compare the two areas quickly:

By adding the outlines of the Antarctic Peninsula over Iceland according to similar positions according to the convection rolls, the coast of the peninsula follows the same trend as the main division line of the Atlantic Ocean as it can be traced over Iceland.

It looks like this on the map base of Náttúrufræðistofnun and Orkustofnun:

The accuracy is quite striking, but again we have to have in mind that the same kind of forces underneath shape the surface. You do not have to look twice:

The comparison is not only made according to latitudes, but general layout of Antarctica compared with the Arctic Ocean. For curious people the drawing on the Google map is shown here:

What was that? Now we can start speculating!

Faxi is not far from Gullfoss and Geysir and has been seen by many on the so called Golden Circle Tour. Again, the alignment of the waterfall is a curiosity. The river Tungufljót makes a turn and forms a waterfall over the cliffs almost in the opposite direction of the river. This feature can be calculated, as the cliffs follow the orientation of convection rolls. This is best shown with a Google map and the relevant drawing and formula:

The direction is N42°E, as the drawing shows E48°N according to the direct result of calculation (with ϕ=64.22).

This could be a coincidence, but many identical results makes it less likely. Just compare this with a former post about Dettifoss (with ϕ=65.80):

The same formula applied at these different latitudes marks the alignment of both waterfalls!

Hraunfossar – the waterfall of no river above it! The beauty and special settings of Hraunfossar can be partly explained. First we have to have in mind its position compared to the convection cell grid, as shown here on the base of a map from Náttúrufræðistofnun and Orkustofnun:

Let us zoom in on this polygon. According to the Convection Cell Model, the upwelling division line creating the Reykjanes Ridge is just at the side of the Hraunfossar waterfall. It can be seen on this Google map:

The small polygon, formed by near-crossing of four division lines between convection rolls, is subject to very clear EW-oriented tectonic settings due to the symmetry of the polygon. The river Hvítá flows accurately along the tectonic EW-axis, leading Hraunfossar to fall southwards into it. Let us now look even closer to realize what this waterfall is all about:

The lava, under which the water flows until it appears in the Hraunfossar waterfall, is considered to have flown in the 10th century. It is called Hallmundarhraun and has partly flown along a valley aligned exactly as the mantle convection line. The direction is E43.8°N. But that is not the ruling direction. A one step analysis of horizontal balance between EW-axis and the convection roll line shows the main outlines of the surrounding landscape. It is marked as a/2 and is aligned E21.9°N. The lava flow has been directed further along the E21.9°N topography alignment as it spread out along the valley of tectonic EW-axis, finally providing this excellent waterfall at the western most end of the lava.