7,3301100 7,3901100 SAL 8 ANU-2308 7,4001100 RAT 1 ANU-3010 7,440 1100 SAL4 ANU-2760 7,5101100 RAT 7 ANU-2650 7,6101120
TABLE 5.3 Radiocarbon ages of shell from midden sites associated with the Teryawynia overflow lakes - arranged in groups geographically spaced from north to south.
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The north side of the blowout consists of lunette sediments. Fine well-sorted sand redeposited from the blowout by recent wind erosion overlies a red palaeosol. Beneath this are fine white sands which auger cores show to rest on red and grey mottled sandy clay.
In other adjacent blowouts brown sediments can be seen
unconformably overlying the red sand. Remains of extinct mammals, the most common being the giant kangaroo Procoptodon , have been found in many of the blowouts and these appear to have been
reworked from the red soil and pure white sands. This
palaeontological evidence indicates that lakes are no younger than late Pleistocene but so far no archaeological remains older than 8,000 years have been found. Archaeological sites in this series of blowouts have only been recorded from the brown sediments or when these are absent, from the surface of the red soil. This suggests that the red soil predates human occupation of the area and that the unconformity at the junction of the red soil unit and overlying sedimentary units may represent a considerable time period.
Ratcatchers Lake is, however, atypical of the lakes in the Teryawynia system whose eastern margins are characterised by relatively uneroded, low, buff coloured clay lunettes. Most of the recorded sites were found on the crest of the clay lunettes. A few occur on the red soil of the western side of the lakes and on remnant beach sediments. Others were found in dune-like landforms of uncertain origin, associated with shallow depressions at the southern end of the lake chain. Despite their diverse stratigraphic situations, the 90 sites recorded around the Teryawynia Creek overflow lakes represent a relatively short time period of between 8000-6000 years BP.
Sites at the southern end of the system are older than those
upstream, suggesting that high critical input of water into the system about 8000 years ago lead to wider occupation of the area and that people moved up the chain as the lower lakes became dry.
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4. The existing Darling River channel
In contrast to the ancestral river channel, few sites associated with the existing river channel have been recorded. This is partly because the modern channel has not been as extensively surveyed but it is also true that older sediments are not well-exposed and only recent sites are visible. This is reflected in the radiocarbon dates for shell from
middens associated with the Darling River which are listed in Table 5.4. R A D I O C A R B O N A G E Y E A R S B P A e o l i a n s a n d G r e y f l u v l a t l e s e d i m e n t s R e d s o i l 0 - 2 0 0 0 M AL 1 A N U - 2 9 9 8 [ 9 9 .2 ± 0 .9 % M ] D W K 3 A N U - 2 7 5 7 [ 5 8 0 ± 7 5 ] D W K 1 A N U - 2 6 5 1 ( 7 1 0 ± 9 0 ] M AL 5 A N U - 3 2 8 9 [ 5 5 0 ± 7 0 ] 2 0 0 0 - 4 0 0 0 D E A 1 A N U - 3 0 0 5 [ 2 2 1 0 1 7 0 ] T A B L E 5 : 4 . R a d io c a r b o n a g e s o f m id d e n s i t e s a s s o c i a t e d w ith th e e x is t in g D a r lin g R iv e r c h a n r a »1.
Most of the floodplain of the Darling River is covered with recent grey fluviatile sediments although there are a few exposures of red soil in cliffs, resembling those on the Talyawalka Creek. The modern river channel has less frequent meanders and therefore fewer cliff exposures than the ancestral stream. In addition only two source-bordering dune accumulation have been recorded. One along the border of the channel on Black Gate Station, is an elongate series of low mounds of white sand about lm high. Three middens (MAL 1-3) and several burials were found within these deposits. Shell from one of the middens gave a modern date and it is assumed that all are of similar age. These sites may have been associated with Aboriginal workers on a pastoral
property, the ruins of which are situated about 300m to the south-west. Shell from a second source-bordering dune (WLC 1) near Wilcannia gave a date of 15,090 ± 130 (ANU-4318).
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Of the remaining 19 recorded sites on the existing Darling River, five were fragmented surface scatters on exposures of red soil and the other 14 on occurred grey floodplain silts.
5. Lakes associated with the existing Darling River channel
Lakes associated with the modern river channel include Lake Menindee and its overflow lake - Lake Cawndilla, Pamamaroo Lake, and Emu, Tandure, Bijiji, Balaka and Malta Lakes. At present these lakes fill when the river overflows during floods and, once filled, retain their water without any further input for up to two years, before they completely evaporate. The lake levels are also lowered after a flood through water flowing from the lakes back into the river.
Substantial lunettes border both Lakes Menindee and Cawndilla but the rarity of archaeological material, especially shell, within them, inhibits the establishment of a satisfactory chronology for their
stratigraphic sequences. Radiocarbon dates associated with these lakes are listed in Table 5.5.
R A D I O C A R B O N A G E