Field guide - IUGS

Stop No 1. Plateau-like summit of the Alluaiv Mountain (1051 m a.s.l.)
Alluaiv plateau-like summit (N-W Lovozero Mountains) is accessible by car up to the top of
1000-1100 m a.s.l (Fig. 2.1, stop 1). Rocks of lujavrite-foyaite-urtite layered complex,
eudialite nepheline and poikilitic feldspathoid syenites are exposed here.
The signature of weathering. The summit surfaces of Alluaiv Mountain and another points
display extensive signs of prolonged weathering, such as felsenmeers and tors (Fig. 2.4).
The height of the tors reaches 8-10 m. These landforms occupy the top position of almost all
summits of Lovozero Mountains; especially in the more elevated western part. The
surrounding tors have adjacent areas of spacious felsenmeers with different size blocs. The
rare erratic boulders are usual for such weathering landforms (Fig. 2.4).
The top of Alluaiv Mountain is a tor surrounded by felsenmeers with single erratic boulders.
Such landforms take a very long time to form, and they are easily eroded if subject to wetbased
erosional ice flow. Hence, their presence indicates that these surfaces have escaped
glacial erosion through multiple glacial cycles. However, shield erratics, which are commonly
found all over these relict surfaces, indicate that the mountains were indeed completely
overridden by Fennoscandian ice. However, the ice sheet over the mountain summits must
have been cold-based; otherwise, the tors and felsenmeers would have been eroded away. It is
likely that the ice over the plateau was frozen to the bed and slow-moving, protecting it from
erosion.
Glacial erosional landforms. The summit surfaces of Lovozero Mountains are dissected by
st nd
numerous glacial cirques and glacial troughs (U-shaped valleys). The 1 and 2 Raslaka
Cirques, the cirque with Gornoe Lake, the U-shaped upper valleys of Sergevan' River system
and Azimut River on N-W Lovozero Mountains are the forms of this kind (Fig. 2.5 - 2.6).
The floors of the cirques are situated between 600-700m a.s.l. and the headwalls rise above
the cirques up to 1000-1100 m a.s.l. The cirques are opened into U-shaped valleys with rivers
and elongated lakes. Most of the valleys in the peripheral parts of the Lovozero Mountains
show pure fluvial character.
18
Fig. 2.4. The tor and felsenmeers on the top of Alluaiv Mt., N-W Lovozero Mountains (a)