Mark Stephens

College of The Bahamas

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James Rose

Royal Holloway University of London

D. D. Gilbertson

University of Plymouth

Michael I. Bird

James Cook University

Sue McLaren

University of Leicester

Chris Hunt

Visioncare Research

FB Pyatt

Nottingham Trent University

Dana Badang

National University of Malaysia

Alan P. Dykes

Kingston University

Brian Pyatt

Nottingham Trent University

D. P. Mattey

Royal Holloway University of London

Cooperative Institutions

University of Cambridge

Harvard University

Pennsylvania State University

Howard Hughes Medical Institute

Universidade de São Paulo

Oxford Archaeology

University of York

Royal Holloway University of London

GE Global Research (United States)

University of Vienna

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Geodiversity of Caves and Rockshelters in Botswana

World geomorphological landscapes (2022)

Mark Stephens Mike De Wit Senwelo M. Isaacs

Siliciclastic

Geodiversity

10.1007/978-3-030-86102-5_14

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Citations (0)

Rainfall trends in Fiji

International Journal of Climatology (2013)

R. Kumar Mark Stephens Tony Weir

ABSTRACT In this article we examine trends in rainfall in the Fiji, using records from 14 stations in Fiji. These records cover more stations and significantly longer periods (>90 years for several stations) than those used in any previous studies. We find that over a period of nearly 100 years there is high interannual variability but no significant long‐term trend in annual rainfall in Fiji in either ‘wet‐side’ or ‘dry‐side’ stations. This result is consistent with the more restricted results of almost all previous studies. We also find no significant trends in ‘wet season’ and ‘dry season’ rainfall, considered separately. Thus unlike temperature data, rainfall data from Fiji provides little evidence of long‐term climate change. There is an indication that the few dry seasons with rainfall more than one standard deviation below the mean have occurred more frequently in the most recent 50 years than in the previous 50. Our results confirm that there is a significant influence of the El Niño Southern Oscillation on rainfall in Fiji, especially on the ‘dry’ side of the larger islands. However, we find that the Interdecadal Pacific Oscillation (IPO) does not modulate the correlation between rainfall in Fiji and the Southern Oscillation Index; contrary to the case in eastern Australia, this correlation is strongly positive for all phases of the IPO .

Dry season

10.1002/joc.3779

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Location-based environmental factors contributing to rainfall-triggered debris flows in the Ba river catchment, northwest Viti Levu island, Fiji

Landslides (2017)

Mark Stephens John H. Lowry Arishma R. Ram

Mass movement

Elevation (ballistics)

Debris flow

10.1007/s10346-017-0918-4

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Citations (15)

Optical dating of sediments from the West Mouth

Mark Stephens Richard G. Roberts Olav B. Lian

Optical dating

Archaeomagnetic dating

Absolute dating

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The cave entrance sequences and environmental change

D. D. Gilbertson Sue McLaren Mark Stephens Chris Hunt James Rose

[Extract] This chapter sets out the primary evidence gathered by the Niah Caves Project concerning the Late Quaternary (i.e. Late Pleistocene and Holocene) sequences in the two main cave entrances that we investigated: the northern chamber of the West Mouth of the Great Cave (Fig. 3.1), and Lobang Hangus. From our initial visits to the West Mouth, studies of the exposures there showed that it has not been the site of continuous or even semi-continuous 'vertical aggradation' of sediments over time, as Tom Harrisson argued: the visual picture is far from uniform, the nature of erosion and deposition has altered significantly through time and space, and there is no simple stratigraphic sequence. As a result, the interpretation of the inherent variability and distribution of the often complex deposits and landforms, including archaeological features, has to depend upon a substantial body of new evidence. This includes: the formal identification and description of exposures; more detailed sedimentological and palynological studies of individual strata recognized in the analysis of 'long' sections through them; and the definition and mapping of the most important components of the sequence, both erosional and depositional, including the contacts between the surviving features. The primary evidence for the new interpretation of the West Mouth cave entrance sequence is summarized in the line drawings and photographs of the exposed faces investigated by the project (their locations shown in detail in Figs. 2.38, 2.39, 3.1 & 3.2; and in Table 3.1). The analysis is based upon new radiocarbon dates of fragments of charcoal excavated from exposures during the NCP project, and which have clear stratigraphic associations. These dates, calibrated using the protocols of Reimer et al. (2009), are listed in the Appendix and reported in this chapter using the terminology in Rose (2007). Further details are set out in Volume 2, Chapter 5 and in the associated supplementary material describing the key exposures in the West Mouth. Further information on the sequence at Lobang Hangus is likewise presented in Volume 2, Chapter 4.

Sequence (biology)

Landform

Aggradation

Chronology

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Palaeoclimate and pedosedimentary reconstruction of a middle to late pleistocene loess-palaeosol sequence, prymorske, sw Ukraine

Studia Quaternaria (2002)

Mark Stephens Dariusz Krzyszkowski A. Ivchenko Marek Majewski

Paleosol

Sequence (biology)

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Investigating groundwater and surface water interactions using stable isotopes and hydrochemistry in the Notwane River Catchment, South East Botswana.

Journal of Hydrology Regional Studies (2022)

Leatile Modie Piet K. Kenabatho Mark Stephens Tlou Mosekiemang

The ephemeral Notwane River Catchment (NRC) is situated in semi-arid Southeast (SE) Botswana. It is part of the Ramotswa Transboundary Dolomitic Aquifer (RTBDA) in the Limpopo basin, shared by Botswana and South Africa. Stable isotopic composition of deuterium (2H) and oxygen (18O) of the water molecule and water chemistry of groundwater and surface water (GW and SW) including rainfall samples were used to assess GW-SW interactions in the NRC. In addition, the seasonal effects on GW-SW interactions were also evaluated. As such, sample collection excursions were timed to coincide with the wet- and dry seasons, respectively. GW and SW were found to have similar chemical characteristics. The major ions in both water types were Ca2+ and HCO-3 in both the dry- and wet season. There was a clear inverse relationship between ground relief and/or elevation and the concentration of chloride ions (mg/L) and electrical conductivity (µS/cm). That is, higher concentrations of chlorine were measured downstream compared to upstream and vice versa. The same trend was manifested for EC levels. Overall, the data indicated the existence of some highly active groundwater recharge sites along the Notwane River, that may be responsible for the aquifer recharge during above-normal rainfall events. In addition, the data revealed albeit inconclusively that GW-SW interactions in the NRC are likely to be influenced by an interplay of several factors such as: (a) the difference in water levels between the river and the adjacent groundwater table (b) the hydrogeology and location of the river channel because geologic formations such as faults and karsts play a critical role in GW-SW interactions. Karsts are known to support groundwater recharge which is different from the nearby semi-arid Kalahari region where recharge is driven by soil profile.

Dry season

δ18O

10.1016/j.ejrh.2022.101014

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Citations (29)

Palaeoenvironments of Ancient Humans in Britain: The Application of Oxygen and Carbon Isotopes to the Reconstruction of Pleistocene Environments

Developments in quaternary science (2011)

Ian Candy Mark Stephens Jonathan Hancock Ruth Waghorne

Tufa

10.1016/b978-0-444-53597-9.00003-0

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Citations (18)