How "Kaldalon Kames" are formed

The "Kaldalon kames" at the base of the Votubjorg cliff, on the south side of the glacial trough.  In places there are clear trenches or gullies behind them, cut against bedrock exposures. 

They are very prominent features.........

The landforms which are most difficult to explain in the Kaldalon Valley in NW Iceland are the elongated features on the valley sides that are referred to variously by assorted researchers as "lateral moraines" or as "kame terraces".  Some refer ro them as being made predominantly of fluvioglacial sands and gravels, while others say they are made predominantly of till or moraine, and others say that they are essentially made of scree or rockfall debris.  Actually we are all right, because the characteristics of these ridges vary, depending on where you happen to look or where you dig your hole in the ground.

I have been examining some of the archive photos from 1960 and 1974, and from the work we did around the glacier snout one can see what the key processes and development stages are.

Stage 1.  On this satellite image you can see that the meltwater river is tight up against the western rock wall of the trough.  Here, because of enhanced ablation or melting, the glacier cross profile is convex.  This means there is a trough or gully along the glacier edge, into which surface meltwater is channelled.  This meltwater comes from surface streams on the bedrock on the glacier flanks or from surface glacier streams from higher up the glacier.

Stage 2.  As melting proceeds, the surface meltwater streams disappearinto the glacier, and most high-volume flow occurs sub-glacially, in tunnels beneath the ice but still against the rock wall.   View towards the rock wall, showing cascades of meltwater flowing down towards  and then into the glacier.

One of the subglacial drainage routes, now abandoned.

Stage 3.  The ice marginal gully is still visible, but it is dry because all meltwater has now been diverted beneath the ice.  Surface morainic debris (including till and faceted, abraded and striated boulders) begins to accumulate in the abandones stream gully.  There are additional inputs from rockfall debris and scree cones derived from the high overlooking basalt cliffs.

Simultaneously, fluvioglacial materials accumulate in the main stream discharge routes, within and along the edge of the glacier.

Stage 4.  Deglaciation and glacier retreat leaves high marginal terraces on the valley side composed of fluvioglacial materials below and capped withy a mixture of till and rockfall debris.  This association is NOT the resuklt of ice front oscillations, but simply a consequence of the meltout process. The ridge is broken into segments, but overall the gradient is down towards a past snout position on the valley floor.

PS. Eskers are often capped with morainic debris in open landscape situations, and with rockfall debris in constrained valley situations.  Here we have both.