**4.1 Physiography**

The Ingrid Christensen Coast is marked by a zig-zag coast line with sporadic occurrence of low lying hills. Theses hills are over ridden by continental ice sheet

**29**

**Figure 8.**

*summer and the continental ice sheet marking coast line.*

*Geomorphological Insight of Some Ice Free Areas of Eastern Antarctica*

towards south exhibiting steep gradient. The Polar Record Glacier, the Polar Times Glacier and the Polarforschung Glacier flow west of Larsemann Hills in the Publication Ice shelf as a part of the Lambert Glacier system. The Publication Ice shelf itself marks a very steep margin east of Polar Record Glacier till it ends abruptly south east of Bolingen Islands. Fjords, such Thala, Quilty and Clemence have cut deep into the ice reaching the ice sheet while Nella fjord has made its way

The Larsemann Hills exhibit horst and graben structures, signifying a tectonic control in their disposition. The Stornes Peninsula, Grovnes Promontory, Fischer Island and Broknes Peninsula from west to east, are conspicuous as horsts with their straight N-S to NNE–SSW trending margins with Thala fjord, Quilty Bay, Clemence Fjord and Nella Fjord respectively flowing in the complimentary grabens (**Figure 7**). The hills are totally devoid of peaks and show low hummocky and rounded tops with isolated erratic boulders on top (**Figure 8**). The general elevation varies between 50 and 70 m above m.s.l. with some parts approaching ~100 m above m s l. The hills are dissected by vertical valleys demonstrating past fluvio-glacial action. The hill tops show weathered surfaces with pits while the windward sides show cavernous pits at places. Moraines are rare. The landscape is dotted with more than 150 water bodies which have been mapped and numbered systematically by [25]. While most of the lakes are shallow up to 3 m depth, and may be classified as ephemeral ponds, there are some deep lakes such as Lake Progress (34 m) in Broknes Peninsula, Lake Oskar in Stornes Peninsula (18 m) and lake LH 7 (14 m) in Grovnes (Bharati) Promontory. Some lakes are saline in nature due to close vicinity of the ocean and the wind born salt spray and/or excessive evaporation and support

Earlier records [26, 27] have given an account of the post glacial regional climate variability along the East Antarctic coastal margin. A detailed description of the region (ANARE reports) and of the microbial communities inhabiting the lakes of Larsemann Hills are provided elsewhere [28–30]. The minimum age of deglaciation of the islands has been inferred to be late Pleistocene/early Holocene. However, reconstruction of relative seal level (RSL) records [31] have stressed that the presence of marine sediments with radiocarbon ages ranging from 40 to 30 ka BP to the east of Filla Island suggest that deglaciation of some areas could have commenced much earlier. Diatom abundance and fossil pigment records [32, 33] also opine that Larsemann Hill were not fully covered by ice during the LGM and gradually deglaciated between c. 13.5 and 4 ka BP. Relatively wet conditions prevailed between c. 11.5 and 9.5 ka BP in a lake on one of the northern islands in the Larsemann Hills [26]. Basal samples from a sediment core at ~158 cms in Larsemann Hills revealed presence of a marine sediments [34] while two more records based on diatom

*Larsemann Hills. Low hills with hummocky tops near Grovnes promontory. Note the open sea in austral* 

*DOI: http://dx.doi.org/10.5772/intechopen.94445*

through a valley in the Broknes Peninsula.

a thick biomass mat in upper levels. .

#### *Geomorphological Insight of Some Ice Free Areas of Eastern Antarctica DOI: http://dx.doi.org/10.5772/intechopen.94445*

*Glaciers and the Polar Environment*

are in conformity with results of other studies, as documented above. Further, the geochemical proxies (TC%, TN%, C/N ratios, δ13C and δ 15N) along with the physical proxies (grain size: sand-silt-clay) for three different periglacial lakes viz., Long Lake, Zub Lake and Sandy Lake [1–3] spanning the glacial–interglacial variations (spanning up to 43 cal ka BP). These studies presents the evolution of lake through reconstruction of productivity patterns, source of organic matter and the hydrological processes through grain size variation complimenting the environmental magnetism records from the same lakes [5, 6]. The deglaciation history from the above observation suggest most likely that parts of Schirmacher Oasis were ice-free even during the LGM. This can be supported records of consistency in the continuity of the sedimentary sequences. However, parts of Schirmacher Oasis became ice free during the last deglaciation i.e., Termination 1. Hence, to better understand the deglaciation history of Schirmacher Oasis, the sedimentary records needs to be supplemented by further studies using novel techniques such as cosmogenic dating

The Larsemann Hills represents one of the largest coastal ice free area of Antarctica, located in the Prydz Bay Region on the Ingrid Christensen Coast. The area is comparatively free of ice shelf with hills protruding in the sea as two prominent peninsulas- Broknes and Stornes Peninsula. In between these two, smaller landmasses namely Grovnes and Brattnevet promontory and several smaller islands (McLeod, Fisher, and Bens etc.) dot this region (**Figure 7**). The area exposes Proterozoic felsic/gneissic basement, overlain by a pelitic and psammitic paragniesses rocks, dominated by medium to coarse grained garnet bearing gneisses as compared to Archean gneisses with s crossing cutting mafic dykes found in Vestfold Hills.

The Ingrid Christensen Coast is marked by a zig-zag coast line with sporadic occurrence of low lying hills. Theses hills are over ridden by continental ice sheet

*Map of Larsemann Hills showing major ice free hills. (https://www.antarctica.gov.au/).*

of rock outcrops and erratic all across Schirmacher Oasis.

**4. Larsemann Hills/Prydz Bay Area**

**4.1 Physiography**

**28**

**Figure 7.**

towards south exhibiting steep gradient. The Polar Record Glacier, the Polar Times Glacier and the Polarforschung Glacier flow west of Larsemann Hills in the Publication Ice shelf as a part of the Lambert Glacier system. The Publication Ice shelf itself marks a very steep margin east of Polar Record Glacier till it ends abruptly south east of Bolingen Islands. Fjords, such Thala, Quilty and Clemence have cut deep into the ice reaching the ice sheet while Nella fjord has made its way through a valley in the Broknes Peninsula.

The Larsemann Hills exhibit horst and graben structures, signifying a tectonic control in their disposition. The Stornes Peninsula, Grovnes Promontory, Fischer Island and Broknes Peninsula from west to east, are conspicuous as horsts with their straight N-S to NNE–SSW trending margins with Thala fjord, Quilty Bay, Clemence Fjord and Nella Fjord respectively flowing in the complimentary grabens (**Figure 7**). The hills are totally devoid of peaks and show low hummocky and rounded tops with isolated erratic boulders on top (**Figure 8**). The general elevation varies between 50 and 70 m above m.s.l. with some parts approaching ~100 m above m s l. The hills are dissected by vertical valleys demonstrating past fluvio-glacial action. The hill tops show weathered surfaces with pits while the windward sides show cavernous pits at places. Moraines are rare. The landscape is dotted with more than 150 water bodies which have been mapped and numbered systematically by [25]. While most of the lakes are shallow up to 3 m depth, and may be classified as ephemeral ponds, there are some deep lakes such as Lake Progress (34 m) in Broknes Peninsula, Lake Oskar in Stornes Peninsula (18 m) and lake LH 7 (14 m) in Grovnes (Bharati) Promontory. Some lakes are saline in nature due to close vicinity of the ocean and the wind born salt spray and/or excessive evaporation and support a thick biomass mat in upper levels. .

Earlier records [26, 27] have given an account of the post glacial regional climate variability along the East Antarctic coastal margin. A detailed description of the region (ANARE reports) and of the microbial communities inhabiting the lakes of Larsemann Hills are provided elsewhere [28–30]. The minimum age of deglaciation of the islands has been inferred to be late Pleistocene/early Holocene. However, reconstruction of relative seal level (RSL) records [31] have stressed that the presence of marine sediments with radiocarbon ages ranging from 40 to 30 ka BP to the east of Filla Island suggest that deglaciation of some areas could have commenced much earlier. Diatom abundance and fossil pigment records [32, 33] also opine that Larsemann Hill were not fully covered by ice during the LGM and gradually deglaciated between c. 13.5 and 4 ka BP. Relatively wet conditions prevailed between c. 11.5 and 9.5 ka BP in a lake on one of the northern islands in the Larsemann Hills [26]. Basal samples from a sediment core at ~158 cms in Larsemann Hills revealed presence of a marine sediments [34] while two more records based on diatom

#### **Figure 8.**

*Larsemann Hills. Low hills with hummocky tops near Grovnes promontory. Note the open sea in austral summer and the continental ice sheet marking coast line.*

records and geochemical proxies suggest presence of marine sediments during mid-Holocene [3, 35] and while diatoms endemic to sub-Antarctic island corresponding to MIS 5e stage were recorded from Broknes Peninsula (Last Interglacial) [33, 36]. The reduced elevation and planation surfaces must have been carved before the LGM facilitating the marine transgression. Based on the variation of diatom population present in sediments suggest that the influence of seawater got weakened after ~5000 yrs. BP [37] and relative warmer climatic condition was prevalent [37, 38]. Core studies from a lake in Grovnes Promontory by [39] have shown high productivity between ~8.3 to ~6 cal ka BP and that the ice free conditions prevailed around 4 cal ka BP.
