Schmidt-hammer exposure-age dating: a review of principles and practice

Matthews, John A.; Winkler, Stefan

doi:10.1016/j.earscirev.2022.104038

Cited by 17 publications

(10 citation statements)

References 197 publications

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“…On the basis of a large number of SHD applications to gneissic rock surfaces in southern Norway, sample sizes of at least 200 R ‐values are sufficient to ensure an age resolution of <1000 years (Matthews & Winkler 2022). R ‐Value distributions from the moraine ridges (Fig.…”

Section: Methodsmentioning

confidence: 99%

“…R ‐Value distributions from the moraine ridges (Fig. 4) show symmetrical distributions with little or no evidence of departure from normality (see also the skewness and kurtosis values in Table 3) or multimodality that might indicate boulder populations of mixed age (Matthews & Winkler 2022). Combining the data from adjacent sites was expected to produce an age resolution of ~500 years or less, while subsamples of 100 impacts permitted the inspection of within‐site R ‐value variability and the detection of possible post‐depositional disturbance effects.…”

Section: Methodsmentioning

confidence: 99%

“…No abrasive pretreatment of the rock surfaces was attempted prior to Schmidt hammer measurement on the grounds that artificial abrasion is likely to remove weathering as well as non‐weathering roughness effects and therefore to be counterproductive in the context of SHD (see discussion in Matthews & Winkler 2022). Similarly, apart from the rejection of particular anomalous R ‐values for specific reasons for which there was evidence (such as slippage of the instrument during measurement or the presence of structural flaws at the point of impact), no systematic rejection of high‐ or low‐value outliers was deemed necessary or beneficial.…”

Section: Methodsmentioning

confidence: 99%

“…It involved establishing linear numerical relationships (calibration equations) between R ‐value and rock‐surface age using two (young and old) control surfaces of known age. This ‘two‐point’ solution to age calibration was first proposed by Matthews & Owen (2010), and has since been widely applied (see Matthews & Winkler 2022). In this paper we have used several sites on boulders and/or bedrock, which have been weighted equally and combined to establish each control point.…”

Section: Methodsmentioning

confidence: 99%

“…Our first objective was to establish the age of the moraines using two complementary exposure‐age dating techniques: 10 Be and Schmidt hammer exposure‐age dating (SHD). The latter technique is used to provide independent, complementary age estimates that can be obtained relatively easily and non‐destructively from a large sample of rock surfaces at the same sites (Matthews & Winkler 2022), allowing data to be collected with little or no disturbance of wildlife or compromise of the natural environmental, aesthetic, archaeological, historical or cultural value of the sites. The second objective was to reconstruct the ELA at the time of moraine‐ridge deposition and hence to determine the equilibrium‐line depression (ΔELA), which is indicative of the palaeoclimatic environment of the former glaciers relative to the present‐day glaciers at these sites.…”

Section: Figmentioning

confidence: 99%

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Deglaciation of the highest mountains in Scandinavia at the Younger Dryas–Holocene transition: evidence from surface exposure‐age dating of ice‐marginal moraines

Matthews,

Linge,

Nesje

et al. 2023

Boreas

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Surface exposure–age dating was applied to rock surfaces associated with ice‐marginal moraines at elevations of ~1520–1780 m a.s.l. on the slopes of Galdhøpiggen and Glittertinden, the two highest mountains in Scandinavia located in the Jotunheimen mountains of central southern Norway. This is important for understanding the pattern and timing of wastage of the Scandinavian Ice Sheet at the Younger Dryas–Holocene transition. Cosmogenic exposure dating (here 10Be dating) of boulders from the moraine ridges yielded overall mean ages (corrected for glacio‐isostatic uplift, surface erosion and snow shielding) of ~11.6 ka from Galdhøpiggen and ~11.2 ka from Glittertinden. Similar 10Be ages were also obtained from additionally collected proximal and distal erratic boulders and bedrock samples. These enabled age calibration of Schmidt‐hammer R‐values and independent Schmidt‐hammer exposure‐age dating (SHD) of the moraine ridges, which yielded comparable mean SHD ages of ~10.8 and ~10.6 ka from the Galdhøpiggen and Glittertinden sites, respectively. Taking account of the age resolution and other limitations of both dating techniques, the results suggest that the two sets of moraines have approximately the same age but that neither technique can distinguish unambiguously between moraine formation in the late Younger Dryas or Early Holocene. Together with features of moraine‐ridge morphology and estimates of equilibrium‐line altitude depression of ~360–575 m (corrected for land uplift), the results imply moraine formation during short‐lived re‐advances of active glaciers, at least the lower reaches of which were warm‐based. It is concluded that the local glaciers remained active and advanced during deglaciation either very late in the Younger Dryas or very early in the Holocene, possibly in response to the Preboreal Oscillation at ~11.4 ka. The study supports the concept of a thin Younger Dryas ice sheet and places time constraints on the timing of final deglaciation in southern Norway.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

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Deglaciation of the highest mountains in Scandinavia at the Younger Dryas–Holocene transition: evidence from surface exposure‐age dating of ice‐marginal moraines

Matthews,

Linge,

Nesje

et al. 2023

Boreas

Self Cite

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Quantifying the effects of carborundum rock surface smoothing for Schmidt hammer R‐value metrics measured on glacial erratics in the North American Great Lakes region

Shepherd,

Portenga,

Peplinski

2024

Earth Surf Processes Landf

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Schmidt hammer R‐values, which reflect the degree of rock surface weathering, can be paired with independent rock surface exposure ages to produce Schmidt hammer exposure‐age dating (SHD) calibration curves that are used to provide rapid estimations of exposure ages for undated rock surfaces. In this Letter, we lay the groundwork for later establishing a SHD calibration curve based on glacial erratics deposited by the Laurentide Ice Sheet in the North American Great Lakes region. First, we establish a reference R‐value for a calibration boulder, which may be used to facilitate direct comparison of R‐values collected by different individuals using mechanical N‐type Schmidt hammers, specifically. We then assess how no, light or heavy use of a carborundum puck to smooth rock surfaces affects resulting R‐value data. Lastly, we compare two different R‐value metrics on the same rock surface: Rmean (n = 30) versus ΔR (Rmax − Rmin of five consecutive R‐values on the same spot). In all assessments, Rmean is similar for erratic surfaces with no and light surface treatment, and both are significantly lower than Rmean of surfaces with heavy treatment. Thus, we advise against the use of heavy surface treatment in SHD applications. We observe no relationship between inferred erratic age and either Rmean or ΔR, which could arise from inferred ages of erratics being inaccurate, from inferred ages of erratics being too similar or from measuring too few erratics from each landform.

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Explaining the Increase in “High-quality Chert” in the Early Upper Paleolithic Artifacts in Southern Jordan: Quantitative Examination of Chert Mechanical Properties and Fracture Predictability

Suga,

Tsukada,

Tarawneh

et al. 2023

J Paleo Arch

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In the studies of aked stone tools, the "quality" of lithic raw material has often been assessed from a viewpoint of its suitability to lithic production, and several studies quanti ed such raw material qualities by measuring mechanical properties of several different rocks like obsidian, chert, and basalt. To advance this approach, this study aims to quantify variations in the quality of chert, which is usually based on the difference in grain-size, e.g., ne-grained chert as "high-quality". For this purpose, we measured two types of hardness, i.e., the rebound hardness by Schmidt Hammer and the Rockwell Hardness (HRC), by using chert samples from southern Jordan, where the use of ne-grained chert increased in the Early Upper Paleolithic (Ahmarian) in association with the development of bladelet technology. The results indicate that ne-grained chert has greater fracture predictability and particularly suitable for the production of bladelets. However, ne-grained chert in southern Jordan suffer from abundant internal fractures and was not used as often as medium-grained chert for Levallois products and robust blades in the Late Middle and Initial Upper Paleolithic. Thus, explaining the prehistoric selectivity of lithic raw materials need to consider fracture predictability as well as other factors, such as actual conditions of occurrences and lithic production technology.

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Schmidt-hammer exposure-age dating: a review of principles and practice

Cited by 17 publications

References 197 publications

Deglaciation of the highest mountains in Scandinavia at the Younger Dryas–Holocene transition: evidence from surface exposure‐age dating of ice‐marginal moraines

Deglaciation of the highest mountains in Scandinavia at the Younger Dryas–Holocene transition: evidence from surface exposure‐age dating of ice‐marginal moraines

Quantifying the effects of carborundum rock surface smoothing for Schmidt hammer R‐value metrics measured on glacial erratics in the North American Great Lakes region

Explaining the Increase in “High-quality Chert” in the Early Upper Paleolithic Artifacts in Southern Jordan: Quantitative Examination of Chert Mechanical Properties and Fracture Predictability

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