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Deposits in sea caves found along the southern coastline of South Africa have produced a rich and detailed archaeological record of early modern humans. There is, however, little evidence for coastal cave deposits and human occupation older than MIS5e (∼120 ka). Based on the correlation of four different chronological methods we present evidence for remnant cave deposits of 1.1–1.0 Ma from the quartzite sea cliff of Pinnacle Point, near Mossel Bay. Initial uranium–thorium ages at isotopic equilibrium indicated an age of >500 ka for two flowstone layers, confirmed by uranium–lead dating of these flowstones from 1.099 ± 0.012 to 1.047 ± 0.011 Ma. TT-OSL (thermally transferred optically stimulated luminescence) provides an age of 1.02 ± 0.088 Ma for the sand grains imbedded in the tufa underlying the flowstone and 0.720 ± 0.066 to 0.665 ± 0.056 for the overlying beach sediments, producing an internally consistent age sequence centring on 1.0–1.1 Ma. The normal palaeomagnetic signal of the younger section of the flowstone is interpreted to represent the Jaramillo between 1.07 and 0.99 Ma. There is a clear hiatus in the middle of this flowstone, leading us to interpret the lower normal signal as the Punaruu event at ∼1.115–1.1051 Ma. Together these four techniques point to an age of 1.1–1.0 Ma for these cave deposits at Pinnacle Point, far older than anticipated. The persistent presence of these 1.1–1.0 Ma deposits means that the enigmatic lack of Earlier Stone Age (Acheulean) artefacts in the sea caves along this coastal region can no longer be explained entirely by the age of the caves or through removal of sediments by previous sea level highstands. We believe that these and other coastal caves from this region, if located high enough above sea level, may contain deposits of great antiquity, which could provide outstanding records of climate, environment, sea level change, and human occupation back into the early to middle Pleistocene.

Deposits in sea caves found along the southern coastline of South Africa have produced a rich and detailed archaeological record of early modern humans. There is, however, little evidence for coastal cave deposits and human occupation older than MIS5e (∼120 ka). Based on the correlation of four different chronological methods we present evidence for remnant cave deposits of 1.1–1.0 Ma from the quartzite sea cliff of Pinnacle Point, near Mossel Bay. Initial uranium–thorium ages at isotopic equilibrium indicated an age of >500 ka for two flowstone layers, confirmed by uranium–lead dating of these flowstones from 1.099 ± 0.012 to 1.047 ± 0.011 Ma. TT-OSL (thermally transferred optically stimulated luminescence) provides an age of 1.02 ± 0.088 Ma for the sand grains imbedded in the tufa underlying the flowstone and 0.720 ± 0.066 to 0.665 ± 0.056 for the overlying beach sediments, producing an internally consistent age sequence centring on 1.0–1.1 Ma. The normal palaeomagnetic signal of the younger section of the flowstone is interpreted to represent the Jaramillo between 1.07 and 0.99 Ma. There is a clear hiatus in the middle of this flowstone, leading us to interpret the lower normal signal as the Punaruu event at ∼1.115–1.1051 Ma. Together these four techniques point to an age of 1.1–1.0 Ma for these cave deposits at Pinnacle Point, far older than anticipated. The persistent presence of these 1.1–1.0 Ma deposits means that the enigmatic lack of Earlier Stone Age (Acheulean) artefacts in the sea caves along this coastal region can no longer be explained entirely by the age of the caves or through removal of sediments by previous sea level highstands. We believe that these and other coastal caves from this region, if located high enough above sea level, may contain deposits of great antiquity, which could provide outstanding records of climate, environment, sea level change, and human occupation back into the early to middle Pleistocene.

Deposits in sea caves found along the southern coastline of South Africa have produced a rich and detailed archaeological record of early modern humans. There is, however, little evidence for coastal cave deposits and human occupation older than MIS5e (∼120 ka). Based on the correlation of four different chronological methods we present evidence for remnant cave deposits of 1.1–1.0 Ma from the quartzite sea cliff of Pinnacle Point, near Mossel Bay. Initial uranium–thorium ages at isotopic equilibrium indicated an age of >500 ka for two flowstone layers, confirmed by uranium–lead dating of these flowstones from 1.099 ± 0.012 to 1.047 ± 0.011 Ma. TT-OSL (thermally transferred optically stimulated luminescence) provides an age of 1.02 ± 0.088 Ma for the sand grains imbedded in the tufa underlying the flowstone and 0.720 ± 0.066 to 0.665 ± 0.056 for the overlying beach sediments, producing an internally consistent age sequence centring on 1.0–1.1 Ma. The normal palaeomagnetic signal of the younger section of the flowstone is interpreted to represent the Jaramillo between 1.07 and 0.99 Ma. There is a clear hiatus in the middle of this flowstone, leading us to interpret the lower normal signal as the Punaruu event at ∼1.115–1.1051 Ma. Together these four techniques point to an age of 1.1–1.0 Ma for these cave deposits at Pinnacle Point, far older than anticipated. The persistent presence of these 1.1–1.0 Ma deposits means that the enigmatic lack of Earlier Stone Age (Acheulean) artefacts in the sea caves along this coastal region can no longer be explained entirely by the age of the caves or through removal of sediments by previous sea level highstands. We believe that these and other coastal caves from this region, if located high enough above sea level, may contain deposits of great antiquity, which could provide outstanding records of climate, environment, sea level change, and human occupation back into the early to middle Pleistocene.

Optically stimulated luminescence (OSL) dating is now commonly used to estimate the depositional age of Quaternary landforms along the southern Cape coast of South Africa. Due to the early onset of dose saturation in the quartz-rich sediments from this region, determining the age of deposits much older than the last three glacio-eustatic sea-level high stands has been a challenge. In this study, we explored the feasibility of using the thermally-transferred OSL (TT-OSL) dating method to obtain ages for aeolian and shallow marine deposits at three different localities that hold promise to further illuminate the long and complex Late Quaternary sea-level history of this region. The bleachability and behaviour of both the recuperated OSL (ReOSL) and the basic-transferred OSL (BT-OSL) signals were investigated, and used as independent chronometers to infer (a) the degree of bleaching of the sediments and (b) the stability of the ReOSL signal for dating of older samples. We examined the sensitivity of both signals to varying preheat temperatures and further developed the single-aliquot regenerative-dose procedure for TT-OSL dating of our samples. To verify our procedures, and to understand some of the underlying mechanisms responsible for the problems we observed, modern analogues and known-age Marine Isotope Sub-stage (MIS) 5e samples from the same localities were also measured. The Middle Pleistocene deposits investigated in this study produced statistically consistent ReOSL and BT-OSL ages compatible with sea-level high stands during Marine Isotope Stage 11. This result is of considerable significance, as it may yield new insights into maximum sea-level heights during this period, which is widely considered an appropriate analogue for future environmental conditions.

Optically stimulated luminescence (OSL) dating is now commonly used to estimate the depositional age of Quaternary landforms along the southern Cape coast of South Africa. Due to the early onset of dose saturation in the quartz-rich sediments from this region, determining the age of deposits much older than the last three glacio-eustatic sea-level high stands has been a challenge. In this study, we explored the feasibility of using the thermally-transferred OSL (TT-OSL) dating method to obtain ages for aeolian and shallow marine deposits at three different localities that hold promise to further illuminate the long and complex Late Quaternary sea-level history of this region. The bleachability and behaviour of both the recuperated OSL (ReOSL) and the basic-transferred OSL (BT-OSL) signals were investigated, and used as independent chronometers to infer (a) the degree of bleaching of the sediments and (b) the stability of the ReOSL signal for dating of older samples. We examined the sensitivity of both signals to varying preheat temperatures and further developed the single-aliquot regenerative-dose procedure for TT-OSL dating of our samples. To verify our procedures, and to understand some of the underlying mechanisms responsible for the problems we observed, modern analogues and known-age Marine Isotope Sub-stage (MIS) 5e samples from the same localities were also measured. The Middle Pleistocene deposits investigated in this study produced statistically consistent ReOSL and BT-OSL ages compatible with sea-level high stands during Marine Isotope Stage 11. This result is of considerable significance, as it may yield new insights into maximum sea-level heights during this period, which is widely considered an appropriate analogue for future environmental conditions.

Optically stimulated luminescence (OSL) dating is now commonly used to estimate the depositional age of Quaternary landforms along the southern Cape coast of South Africa. Due to the early onset of dose saturation in the quartz-rich sediments from this region, determining the age of deposits much older than the last three glacio-eustatic sea-level high stands has been a challenge. In this study, we explored the feasibility of using the thermally-transferred OSL (TT-OSL) dating method to obtain ages for aeolian and shallow marine deposits at three different localities that hold promise to further illuminate the long and complex Late Quaternary sea-level history of this region. The bleachability and behaviour of both the recuperated OSL (ReOSL) and the basic-transferred OSL (BT-OSL) signals were investigated, and used as independent chronometers to infer (a) the degree of bleaching of the sediments and (b) the stability of the ReOSL signal for dating of older samples. We examined the sensitivity of both signals to varying preheat temperatures and further developed the single-aliquot regenerative-dose procedure for TT-OSL dating of our samples. To verify our procedures, and to understand some of the underlying mechanisms responsible for the problems we observed, modern analogues and known-age Marine Isotope Sub-stage (MIS) 5e samples from the same localities were also measured. The Middle Pleistocene deposits investigated in this study produced statistically consistent ReOSL and BT-OSL ages compatible with sea-level high stands during Marine Isotope Stage 11. This result is of considerable significance, as it may yield new insights into maximum sea-level heights during this period, which is widely considered an appropriate analogue for future environmental conditions.

Optically stimulated luminescence (OSL) dating is now commonly used to estimate the depositional age of Quaternary landforms along the southern Cape coast of South Africa. Due to the early onset of dose saturation in the quartz-rich sediments from this region, determining the age of deposits much older than the last three glacio-eustatic sea-level high stands has been a challenge. In this study, we explored the feasibility of using the thermally-transferred OSL (TT-OSL) dating method to obtain ages for aeolian and shallow marine deposits at three different localities that hold promise to further illuminate the long and complex Late Quaternary sea-level history of this region. The bleachability and behaviour of both the recuperated OSL (ReOSL) and the basic-transferred OSL (BT-OSL) signals were investigated, and used as independent chronometers to infer (a) the degree of bleaching of the sediments and (b) the stability of the ReOSL signal for dating of older samples. We examined the sensitivity of both signals to varying preheat temperatures and further developed the single-aliquot regenerative-dose procedure for TT-OSL dating of our samples. To verify our procedures, and to understand some of the underlying mechanisms responsible for the problems we observed, modern analogues and known-age Marine Isotope Sub-stage (MIS) 5e samples from the same localities were also measured. The Middle Pleistocene deposits investigated in this study produced statistically consistent ReOSL and BT-OSL ages compatible with sea-level high stands during Marine Isotope Stage 11. This result is of considerable significance, as it may yield new insights into maximum sea-level heights during this period, which is widely considered an appropriate analogue for future environmental conditions.