A Reconnaissance Study of Glaciation on the Owen Massif CONTINUEDResultsA simplified geomorphological map (Figure 3) of themain features of the central Owen Massif is presented(and see online appendix). The major glacial featuresidentified are U shaped valleys, rounded bedrock hills,lateral moraines, kames, hummocky ground morainesand fluvioglacial veneers. Accessory features includeerratics, and glacio-karst features dominantly suffusiondolines and glaciokarst pavements. Due to their sizeand quantity, dolines and glaciokarst pavements havenot been included in Figure 3. These features have beendivided into glacial erosional and glacial depositionalgroups.Glacial erosional landformsU-shaped valleys, virtually box canyons, are widespreadon the massif (Figure 3 and online appendix). Some ofthese valleys are consistent with regional N–S alignmentsuch as Blue Creek, but others cross cut the structure,such as Granity Pass. All the U shaped valleys transitioninto V-shaped valleys down stream, in some cases, thisis marked by gorges incised into the U shaped valleyfloor. The U shaped valley floor shoulders above thegorges sometimes have a cover of hummocky groundmoraine. The U-shaped valleys terminate abruptly at themassif edge but a north-south aligned U shaped valleyextends 1.5 km north and about 3 km south along thecontact with the Separation Point Granite (Figure 2, 3and online appendix).Glacially smoothed hills and knolls are widespread.These occur on all scales from a few metres to manyhundreds of metres in size. Bedding control is importantbut many of the smaller features align with thelocal U shaped valley systems. Knobs between ReverseBasin and Blue Creek (Figure 4 and 5,a) are the bestexamples of ice smoothed ridges. We do not specificallyidentify cirques, though several good candidates exist,because of the difficulty of separating karst basins fromtrue cirques.Glaciokarst pavements are dotted around the massif.They form parallel or sub-parallel to bedding and joints.Very locally glacial striations and chatter-marks arepreserved on the pavements (Figure 5,b). Most of thepavements, however, have had some dissolution sinceformation and some display frost shattering. Excellentexamples occur north of Replica Hill (E <strong>24</strong>71130, N5963330) and on the east side of Blue Creek (E <strong>24</strong>73630,N 5967120), near the lateral moraine of figure 5,c.Glacial depositional featuresLateral moraines and kame complexes are present ininternal valleys on the massif between Sanctuary Basinand Reverse Basin and north of Billies Knob (Figure 3 &4). The composition of the kame terraces and terminalmoraines is unknown, due to a lack of exposure. Theycomprise ridges that flank the valleys and have ahummocky surface. The amplitude of the hummocks isin the order of a few metres.Hummocky ground moraine (represented by diamictonin Figure 3) is present on some of the floors of theinternal valleys on the massif and on some of the valleyfloors leading to the edge of the massif. The best knownglacial feature on the massif, the so-called railway ridgenear Granity Pass Hut (Figure 3, 4 and 5), is in factremnant ground moraine dissected by drainage tocreate a ridge like feature. This ridge is composed of atleast 15 m of diamicton with frequent striated andfaceted clasts and contains Wangapeka lithologies aswell as rare hornblende rich Andesites. West of the headof this feature is a series of fluvioglacial kame terraces(Figure 3 and 4) which host a set of minor ponds a fewtens of m above the valley floor. The low lying positionsuggests that these were associated with the very last iceoccupying the valley floor.Moderately sorted large pebble to cobble size clastics,with well-rounded, Wangapeka insoluble gravels mantlemany surfaces and benches perched above valley floors(alluvium on Figure 3) indicating fluvial overflowadjacent to former glaciers (Figure 3 and 5,d). There arealso some coarse cobble and gravel remnants on somesharp ridge crests (e.g. between Blue and Granity creek).Valley floor fills are more complex (Figure 6), rangingfrom morainic ridges dissected by streams, clastic andorganic pond and channel deposits. Valley sidematerials and talus are also encroaching onto valleyfloors. Many of these deposits are now becoming pockmarkedby suffusion dolines, except in areas of thickaccumulation like in Poverty Basin (Figure 5,d).Striated and faceted clasts have been collected from amatrix supported, pebble to boulder diamictonoutcropping in poorly exposed, suffusion modifiedmoraine west of Sentenal Hill. The striae in the clastsare aligned at orthogonals along the A–B plane. A singlestriking example of a Wangapeka erratic lodged directlyonto karstified Arthur Marble has been observed at gridreference E <strong>24</strong>71633, N 5964225 (Figure 3).A notable absence is that of marble clasts. <strong>No</strong>ne havebeen recorded in any of the outcrops. An importantquestion is why? Where has all the eroded marble gone?Other LandformsLike many alpine karst areas, the glacial molding of MtOwen is gradually being modified by processes ofsolution and suffusion that lead to re-establishment ofkarst. Frost shattering and mass movements arecompeting with these karst processes (Smart, 2004a).14 | <strong>Quaternary</strong> AUSTRALASIA <strong>24</strong> (2)
Figure 4. (above) Photo ofSanctuary Basin in foreground,with annotated landmarks ofRailway Ridge, ice roundedbedrock hills, kame terraces and alateral moraine.Figure 5. (left) Four photos ofcommon landforms on the massif.(a) Ice smoothed hills (1), with thelargest over 120 metres high and alateral moraine (2). (b) Glaciokarstpavement, north of ReplicaHill, with Mt Patriarch in thebackground. <strong>No</strong>te the smallindentations in to foregroundmarked with arrows and thetruncated karren. (c) Lateralmoraine (approx. 6 metres high)north of Billies Knob, withCulliford Hill in the clouds, leftbackground. The arrow points to ahalf of a person for scale.(d) Poverty Basin, approximately500 metres across, with a thickclastic fill.15 | <strong>Quaternary</strong> AUSTRALASIA <strong>24</strong> (2)
Change language