Multi-proxy stalagmite records from northern California reveal dynamic patterns of regional hydroclimate over the last glacial cycle

doi:10.1016/j.quascirev.2020.106411

Quaternary Science Reviews

Volume 241, 1 August 2020, 106411

https://doi.org/10.1016/j.quascirev.2020.106411 Get rights and content

Highlights

•
Multiproxy, replicated stalagmite paleoclimate record from Northern California.
•
Location of transition between dry and wet regions in western US in response to global paleoclimate events varies in time.
•
Increase in Central Pacific-sourced precipitation not always associated with overall increased rainfall in northern California.

Abstract

Despite its importance for California’s water resources, little is known about how precipitation has varied in far northern California beyond the historical record. We present a new, multi-proxy paleoclimate record derived from two coeval stalagmites from Lake Shasta Caverns (LSC), California that covers the end of Marine Isotope Stage 3 through Heinrich Stadial 1 (∼35,000 to 14,000 years BP). At 40.8°N, LSC is situated within the transition zone between regions in the northwestern and southwestern United States that demonstrate different precipitation responses to both modern and paleoclimatic drivers. Stable isotope and trace element proxies from LSC stalagmites indicate the region experienced wet conditions during interstadials (warm periods) associated with Dansgaard-Oeschger cycles, similar to proxy records from southern Oregon and the northern Great Basin, but in contrast to records from the desert southwest. Similar to the northern Cascades and Rocky Mountains, LSC was drier during the Last Glacial Maximum. However, proxies indicate increased rainfall throughout Heinrich Stadial 1, similar to the Great Basin and southwest. Thus, the LSC record demonstrates the non-stationarity of the transition zone location and illustrates a complex pattern of precipitation response to global climate change in the western United States. Covariation of speleothem δ¹⁸O, an indicator of moisture source, with δ¹³C and trace elements, indicators of moisture amount, suggest a higher proportion of Central Pacific precipitation during the Last Glacial Maximum, despite the enhanced aridity. In contrast, periods characterized by increased precipitation amounts, such as early Heinrich 1, are associated with enhanced moisture from the Northern Pacific.

Introduction

Proxy evidence supports a dynamic hydroclimate across western North America during the last glacial period and deglaciation. Regional proxy compilations illustrate the spatial pattern of hydroclimatic variability in response to the climate of the Last Glacial Maximum (LGM) ∼21,000 yrs BP (Thompson et al., 1993; Bartlein et al., 2011; Oster et al., 2015a; Scheff et al., 2017). Comparisons of terrestrial proxy time series reveal hydroclimatic shifts at millennial and longer time scales, providing evidence for coherent but potentially complex changes during the last deglaciation (Oster and Kelley, 2016; Feakins et al., 2019) and earlier during Marine Isotope Stages 3–5 in response to Dansgaard-Oeschger cycles (Benson et al., 2013; Glover et al., 2017). Comparisons of the timing of pluvial lake highstands and other proxy records have revealed complex regional patterns arising from forcings such as the growth and decay of the Laurentide Ice Sheet, variations in Atlantic Meridional Overturning Circulation, interhemisphere temperature gradients, and the position of the Intertropical Convergence Zone that influence the amount and sources of moisture reaching western North America (Oster et al., 2015a; Morrill et al., 2018; Asmerom et al., 2017; McGee et al., 2018; Hudson et al., 2019). The relative importance of these drivers on different time scales remains a source of active investigation.

Presently, winter precipitation in western North America has been shown to exhibit a north/south, wet/dry dipole pattern on interannual to decadal timescales partly in response to ocean-atmosphere interactions across the Pacific and Atlantic Oceans including the El Niño/Southern Oscillation, the Pacific Decadal Oscillation, and the Atlantic Multidecadal Oscillation (Redmond and Koch, 1991; Wise, 2010). This dipole pattern is associated with both the distribution of total rainfall across the region as well as extreme precipitation events (Dettinger et al., 1998; Jiang et al., 2013). Analysis of tree ring records from across western North America suggests that the transition between wet and dry dipole regions has remained consistently centered around 40°N for the past 500 years (Wise, 2016). A geographically similar dipole pattern is evident in regional hydroclimate variations during the LGM in response to the influence of the Laurentide Ice Sheet on atmospheric circulation (Oster et al., 2015a; Lora et al., 2017). At the LGM, climate models and proxy compilations indicate a transition between wet and dry conditions along the west coast occurred near the California-Oregon border (42 °N) (Oster et al., 2015a). There is further evidence that this dipole pattern persisted during millennial-scale climate oscillations of the last deglaciation (Hudson et al., 2019). However, there are comparatively few paleoclimate records that exist close to the location of this dipole transition zone that possess the potential to track changes in the location and behavior of the dipole at different temporal scales.

Here we present a new, U-series dated, multi-proxy speleothem paleoclimate record from Lake Shasta Caverns (LSC) in northern California (40.804°N, 122.304°W). Given its location, LSC is well-situated to track variations in regional patterns of precipitation change and reveal spatial shifts in the dipole transition zone across the last glacial period and deglaciation (Fig. 1A). We present records of oxygen and carbon isotope and trace element variability in two partly overlapping stalagmites that grew collectively between ∼37,000 and 14,000 yrs BP. These combined proxies allow us to explore how changes in moisture source and amount may have influenced the overall hydroclimate at this location and how this variability may have contributed to regional patterns of climate variability during the last glacial period and in response to Dansgaard-Oeschger cycles and Heinrich Events. Our results demonstrate temporal variability in the dipole pattern and highlight the need for multi-proxy records that can parse changes in moisture source versus amount to examine the relative importance of different hydroclimatic drivers for this hydrologically sensitive region.

Section snippets

Site and description

Lake Shasta Caverns (LSC) is a commercial cave located approximately 32 km north of Redding, California, on the east side of the McCloud arm of Shasta Lake (40.804°N, 122.304°W, 725 m a.s.l.) (Fig. 1A; B). The cave is developed within the McCloud limestone, which crops out in a north-south belt in the Shasta Lake area (Fig. 1B). The McCloud Limestone is Early Permian in age and ranges in thickness from less than 30 m to about 800 m. It consists mainly of calcarenite composed of varying amounts

Water collection and analysis

Through a collaboration with the Lake Shasta Caverns staff, we collected drip water samples at seven locations throughout the cave (Fig. 1C). Three sites have been monitored beginning in December 2015, with water collection at the four other sites beginning at later dates. The drip sites chosen are the most consistently wet locations within the cave. Collections occurred regularly during the cool wet season when drip sites within the cave were more active. Water collections during the summer

Water isotopes

Our analysis of δ¹⁸O and δ²H in rain and drip waters demonstrates that all waters fall near the Global Meteoric Water Line, with similar calculated local meteoric water lines (Fig. 2A; Table S1). Samples of rainwater collected at NADP site CA76 show a wider range of variability than both the limited measurements of rainwater from Lake Shasta Caverns and the LSC drip water. This discrepancy may reflect a few factors. Rainwater samples from site CA76 are available for a longer period of time and

δ¹⁸O and δ¹³C

Analysis of drip water δ¹⁸O and δ²H at LSC demonstrates that drip water isotope values fall along a local meteoric water line (Fig. 2A), suggesting minimal modification of drip waters by evaporation or other epikarst processes. Drip water δ¹⁸O analyzed at multiple sites within the cave also shows similar variability. Furthermore, for the period of time over which LSC drip water and measurements of CA76 rainfall data overlap, they show similar isotopic variability, with δ¹⁸O values decreasing

Conclusions

In sum, records from LSC stalagmites provide novel insights into the glacial/deglacial hydroclimate of western North American as a result of their location near a long-lived hydroclimatic transition and the information they provide on moisture sources and precipitation amounts through several key paleoclimatic events from ∼35,000–14,000 years BP.

The LSC record largely supports the presence of a north/south dipole in hydroclimatic response to forcings on different timescales, indicating that

Credit author statement

Jessica Oster: Conceptualization, Investigation, Formal Analysis, Funding acquisition, Data Curation, Writing-Original draft Isabelle Weisman: Investigation, Formal Analysis, Writing-Original draft Warren Sharp: Investigation, Resources, Validation, Writing-Review and editing.

Data availability

All speleothem data are archived with the NOAA Paleoclimatology Database (https://www.ncdc.noaa.gov/paleo/study/30254).

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

JLO acknowledges support from the National Science Foundation (AGS-1554998) and the National Geographic Foundation (39815). IEW acknowledges support from the Geological Society of America. We thank David Mundt and the Lake Shasta Caverns staff for logistical help during visits to the cave and for collecting water samples, Dr. Ralf Bennartz (Vanderbilt University) for assistance with HYSPLIT analyses, Dr. Peter Blisniuk (Stanford University) and Dr. Hari Mix (Santa Clara University) for

References (78)

R. Belli et al.
Investigating the hydrological significance of stalagmite geochemistry (Mg, Sr) using Sr isotope and particulate element records across the Late Glacial-to-Holocene transition
Geochem. Cosmochim. Acta
(2017)
L.V. Benson et al.
Insights from a synthesis of old and new climate-proxy data from the Pyramid and Winnemucca lake basins for ther period 48 – 11.5 cal. ka., 2013
Quat. Int.
(2013)
A. Borsato et al.
Trace element distribution in annual stalagmite laminae mapped by micrometer-resolution X-ray fluorescence. Implications for incorporation of environmentally significant species
Geochem. Cosmochim. Acta
(2007)
D. Breecker
Atmospheric pCO₂ control on speleothem stable carbon isotope compositions
Earth Planet Sci. Lett.
(2017)
C.E. Briles et al.
Postglacial vegetation, fire, and climate history of the Siskiyou Mountains, Oregon, USA
Quat. Res.
(2005)
W.S. Broecker et al.
A Great Basin-wide dry episode during the first half of the mystery interval?
Quat. Sci. Rev.
(2009)
E. Busenberg et al.
Thermodynamics of magnesian calcite solid-solutions at 25°C and 1 atm total pressure
Geochem. Cosmochim. Acta
(1989)
H. Cheng et al.
Improvements in ²³⁰Th dating, ²³⁰Th and ²³⁴U half-life values, and U-Th isotopic measurements by multi-collector inductively coupled plasma mass spectrometry
Earth Planet Sci. Lett.
(2013)
I.J. Fairchild et al.
Controls on trace element (Sr-Mg) compositions of carbonate cave waters: implications for speleothem climatic records
Chem. Geol.
(2000)
S.J. Feakins et al.
Biomarkers reveal abrupt switches in hydroclimate during the last glacial in southern California
Earth Planet Sci. Lett.
(2019)

M. Berkelhammer et al.

Synoptic and mesoscale controls on the isotopic composition of precipitation in the western United States

Clim. Dynam.

(2012)

J.P. Bradbury et al.

Limnological and climatic environments at Upper Klamath Lake, Oregon during the past 45000 years

J. Paleolimnol.

(2004)

J.P. Bradbury et al.

Environment and paleolimnology of Owens Lake, California: a record of climate and hydrology for the past 50,000 years

H. Cheng et al.

The Asian monsoon over the past 640,000 years and ice age terminations

Nature

(2016)

K. Chou et al.

Comparative study of the kinetics and mechanisms of dissolution of carbonate minerals

Chem. Geol.

(1989)

F. Demirmen et al.

Petrography and origin of permian McCloud limestone of northern California

J. Sediment. Petrol.

(1965)

M.D. Dettinger et al.

North-south precipitation patterns in western North America on annual to decadal timescales

J. Clim.

(1998)

M. Dettinger

Fifty-two years of “pineapple express” storms across the west coast of North America. U.S. Geological survey, scripps institution of oceanography for the California energy commission

Cited by (15)

Effect of mineral growth rate on Zinc incorporation into calcite and aragonite
2024, Chemical Geology
The distribution coefficient of Zn²⁺ (i.e., D^⁎_Zn²⁺) between calcite/aragonite and reactive fluids were estimated as a function of mineral growth rate (10^–8.6 < r_p < 10^–7.3 mol/m²/s) at 25 °C and 1 bar pCO₂. The obtained results suggest that rate strongly influences D^⁎_Zn²⁺ in both minerals and the dependence of D^⁎_Zn²⁺ on growth rate can be described as:
Log D^⁎_Zn²⁺_{, calcite} = −0.331 (±0.048) Log r_p – 0.991 (±0.375); R² = 0.82
Log D^⁎_Zn²⁺_{, aragonite} = 0.751 (±0.089) Log r_p + 5.160 (±0.702); R² = 0.88
These correlations for calcite and aragonite are in agreement with the incorporation of foreign ions in compatible and incompatible host mineral structures, respectively. The use of the surface reaction kinetic model (SRKM) to fit the experimental data provided good results for calcite. In contrast, SRKM was not able to provide a good fit for Zn incorporation in aragonite, underlying the difficulties to model incorporation of foreign elements incompatible with the host mineral structure.
Moreover, a linear correlation was found between D^⁎_Zn²⁺ and the saturation degree of the reactive fluid with respect to the growing mineral phase that can be described as:
Log D^⁎_Zn²⁺_calcite = −1.280 (±0.221) SI_calcite + 1.864 (±0.053); R² = 0.77
Log D^⁎_Zn²⁺_aragonite = 2.852 (±0.418) SI_aragonite - 1.640 (±0.138); R² = 0.82
Considering that SI_mineral = 0 reflects chemical equilibrium in the above equations, a Log D^⁎_Zn²⁺ at equilibrium was calculated for both calcite (1.9) and aragonite (−1.6). This value is in good agreement with the theoretical models for calcite, whereas in the case of aragonite it is 1.5 to 2.1 orders of magnitude lower than the previously published values. While the incorporation of Zn ions into calcite implies the formation of a dilute solid-solution between calcite and smithsonite (i.e. ZnCO₃), the incorporation of Zn ions into aragonite is likely associated to the density of defect sites at the growing mineral surface.
Chronology and climate of the Last Glacial Maximum and the subsequent deglaciation in the northern Medicine Bow Mountains, Wyoming, USA
2023, Quaternary Science Advances
A combination of ¹⁰Be surface-exposure dating of glacially transported boulders and glacially polished bedrock, and numerical modeling of the ∼600 km² Late Pleistocene icefield complex in the northern Medicine Bow Mountains of Wyoming, USA, constrains the timing and climate forcing of the local last glacial maximum (LLGM) and the subsequent deglaciation in the range. The chronology reported here indicates initial recession of the ∼100 km² Libby Creek glacier on the east side of the complex from its terminal moraine at 20.7 ± 2.8 ka, followed by length reduction of 38% by 18.0 ± 0.8 ka and 75% by 14.7 ± 0.4 ka. By 14.2 ± 0.3 ka, the icefield had nearly completely disappeared although there is evidence of two subsequent standstills or minor readvances at ∼11.5 ± 0.5 ka and ∼10.5 ± 0.3 ka. Results of numerical glacier-modeling experiments suggest that the LLGM was associated with temperatures 6.0 °C colder than present with an uncertainty of about ±1.7 °C, assuming no change from modern precipitation. If precipitation differed at the LLGM, over a range from half to twice modern, the temperature depression necessary to sustain the icefield complex could have been as much as 8.0 ± 1.7 °C or as little as 3.1 ± 1.7 °C respectively. As most available proxies and climate-model output suggest mildly decreased precipitation at the LLGM, a temperature depression of somewhat more than 6.0 °C is the most likely scenario. Model experiments further suggest that nearly complete deglaciation by 14.2 ± 0.3 ka involved only a ∼1.7 °C rise from LLGM temperature, assuming no change in precipitation. The sensitivity of the icefield complex to such limited warming reflects its plateau-like hypsometry, which makes it particularly sensitive to changing equilibrium-line altitude. While the precise chronology of deglaciation remains open to interpretation, most of the ice loss preceded the North Atlantic Bølling-Allerød interval (∼14.7–12.9 ka), suggesting that global atmospheric CO₂ and rising summer insolation were the dominant forcings of ice retreat.
Late Pleistocene glaciation in the southernmost Sangre de Cristo Mountains, New Mexico – Chronology and paleoclimate
2023, Quaternary Science Advances
Surface-exposure dating of moraine boulders and numerical paleoglacier modeling yield the first numerical ages for the local Last Glacial Maximum (LGM) in the state of New Mexico and the southernmost Rocky Mountains, and the first glacier-based paleoclimate estimates for that region. Analysis of cosmogenic ¹⁰Be in samples from ten moraine boulders indicates that glaciers in the Winsor Creek drainage in the southern Sangre de Cristo Mountains occupied their LGM positions until ∼21.2 ± 2.0 ka, and likely remained near those positions until about 18.3 ± 1.3 ka. Application of a coupled energy/mass balance and ice-flow model to the reconstructed paleoglaciers indicates that temperature depressions of 8.6–9.0 °C from present temperatures would have been necessary to sustain glaciers in the drainage at their last glacial maximum extents, assuming precipitation amounts and seasonality were no different from modern. Model uncertainly in these estimates is approximately ±1.5 °C. Combining glacier-model output with climate-model output interpolated to the study region suggests that the LGM glaciers in the drainage were likely sustained by a temperature depression of ∼8 °C from modern conditions, coupled with an increase of ∼10–25% in precipitation, at least during the fall-through-spring seasons. Such an increase in accumulation season precipitation is consistent with previous suggestions of enhancement of Pacific-sourced cyclonic precipitation due to southward displacement of the LGM mean winter storm track across the western United States and/or of increased intensity and penetration of Pacific atmospheric rivers into the continent at the LGM.
Variability in effective moisture inferred from inclusion fluid δ<sup>18</sup>O and δ<sup>2</sup>H values in a central Sierra Nevada stalagmite (CA)
2022, Quaternary Science Reviews
Citation Excerpt :
All duplicates were averaged together. We follow the time-interval differentiation for the last deglaciation proposed by Oster et al. (2020): Late Glacial (LG, 19.3 to 18.0; n = 8 samples analyzed), Heinrich Stadial 1a (18.0–16.1 ka, n = 8), Heinrich Stadial 1b (16.1–14.6 ka; n = 8), the Older Dryas stadial (OD, 14.1 to 13.8 ka; n = 5), and the Bölling and Allerød interstadials (14.6–14.1 ka and 13.8 to 12.8 ka, respectively; n = 12). Two phases of Heinrich Stadial 1 have been previously denoted as the “Big Dry” and the subsequent “Big Wet” (Broecker et al., 2009).
The oxygen isotopic composition of stalagmites is widely used to infer regional changes in terrestrial surface temperatures and precipitation dynamics. The stalagmite δ¹⁸O values, however, record the influence of multiple environmental conditions (e.g., temperature, precipitation source and amount) as well as in-cave physicochemical processes and possible disequilibrium precipitation effects. The δ¹⁸O and δ²H values of fluids entombed in stalagmites as inclusions have the potential to be robust proxies of paleo-precipitation δ¹⁸O and δ²H. Here we analyze the inclusion-fluid δ¹⁸O and δ²H values for a stalagmite from a central Sierra Nevada foothill cave, McLean's Cave, to reconstruct changes in effective moisture (precipitation – evaporation) in the region over the last deglaciation (20–13 ka). The results demonstrate high variability in inclusion-fluid δ¹⁸O and δ²H values and further suggest that the δ¹⁸O and δ²H values have several intervals driven by disequilibrium dis oxygen isotopic fractionation. These findings demonstrate that effective moisture was likely lower during past warm periods in comparison to some colder periods, consistent with other stalagmite calcite-based paleoclimate records from the southwestern United States.
Stalagmite multi-proxy evidence of wet and dry intervals in the middle Yangtze Valley during the last glacial period
2022, Palaeogeography, Palaeoclimatology, Palaeoecology
There continues to be debate on the wet and dry conditions in central China due to different geological archives and proxy interpretations. This study reconstructed multi-proxy sequences spanning intervals between 65 and 40 ka using high-precision Th-230 dates, which was carried out on a stalagmite from Yongxing cave in the middle Yangtze Valley located in the Meiyu belt, China. Merely according to the petrography of the sample, Heinrich (H) 5-H6, Dansgaard–Oeschger (DO) 9-DO18 (or even secondary changes including DO15a and DO15b; DO17a, DO17b, and DO17c) were directly identified alongside the oxygen isotope record. The δ¹³C, trace elements, mineralogical, and bio-geochemical proxies exhibited similar millennial changes to that of the δ¹⁸O. This provided an indication of responses to millennial-scale climatic events in the karst hydrological cycle, local environment, and soil vegetation; however, the sensitivities to these events differed. Petrographic analyses of the same stalagmite including scanning electrical microscope (SEM), X-ray diffraction (XRD), fluorescence intensity, the deposition rate, and the diameter index depicted a dry-cold climate during the H events, and a wet-warm climate during the DO cycles in the middle Yangtze Valley. These results are consistent with the peat records of Dajiuhu Lake in the same area. We suggest that a combination of Atlantic Meridional Overturning Circulation (AMOC) and El Niño-Southern Oscillation (ENSO) may exert a strong influence on the Meiyu region and the related precipitation.
Late Pleistocene-Holocene aeolian loess-paleosol sections in the Yellow River source area on the northeast Tibetan Plateau: chronostratigraphy, sediment provenance, and implications for paleoclimate reconstruction
2022, Catena
Two late Pleistocene-Holocene aeolian loess-paleosol sections were identified in the Yellow River source area on the northeast (NE) Tibetan Plateau. Based on the comprehensive study on multiple proxies, AMS ¹⁴C and optically stimulated luminescence (OSL) dates, these two sections have a basal age of 14000–11500 yr BP, suggesting that they accumulated since the last deglaciation. Four stages of paleoclimate evolution can be summarized as follows. (1) A cold-dry period was dominated by the Westerlies in the late Pleistocene (ca. 14000–11500 yr BP). (2) A gradual transition to warm-wet with the weakened Westerlies and strengthened East Asian summer monsoon (EASM) occurred in the early Holocene (ca. 11500–9000 yr BP). (3) A warm-wet episode was under strong EASM in the middle Holocene (ca. 9000–3100 yr BP), however, a cold event was identified at 5000–3500 yr BP, which was caused by the abrupt weakening of the EASM and the strengthening of the Westerlies. (4) A phase of gradually shifting to dry-cold was controlled by the weakened EASM and strengthened Westerlies (after ca. 3100 yr BP). The assemblage of grain-size end-member modelling analysis (EM1-EM5) and heavy minerals indicated that aeolian deposit units have multiple sediment provenances and transport processes. EM1 is clay deposits composed of secondary clay minerals produced during weathering and pedogenesis, whereas EM2 is fine silts derived from distant dust transported through long-existing high-level Westerlies. EM3 and EM4 are coarse silts that originated from the moraines and periglacial deposits in the middle and distant source areas transported by the Westerlies and Tibetan Plateau Monsoon. Lastly, EM5 is sand from fluvial deposits and slope clastics transported by strong valley wind within the local area. This study is helpful to understand the mechanisms of paleoclimate evolution on the NE Tibetan Plateau. It also has important implications for characterizing and subdividing aeolian loess in China.

View all citing articles on Scopus

View full text

Multi-proxy stalagmite records from northern California reveal dynamic patterns of regional hydroclimate over the last glacial cycle

Highlights

Abstract

Introduction

Section snippets

Site and description

Water collection and analysis

Water isotopes

δ18O and δ13C

Conclusions

Credit author statement

Data availability

Declaration of competing interest

Acknowledgements

Geochem. Cosmochim. Acta

Quat. Int.

Geochem. Cosmochim. Acta

Earth Planet Sci. Lett.

Quat. Res.

Quat. Sci. Rev.

Geochem. Cosmochim. Acta

Earth Planet Sci. Lett.

Chem. Geol.

Earth Planet Sci. Lett.

Earth Planet Sci. Lett.

Quat. Geochronol.

Quat. Sci. Rev.

Chem. Geol.

Geochem. Cosmochim. Acta

Quat. Sci. Rev.

Geochem. Cosmochim. Acta

Quat. Sci. Rev.

Quat. Sci. Rev.

Geochem. Cosmochim. Acta

Quat. Res.

Palaeogeogr. Palaeoclimatol. Palaeoecol.

Geochem. Cosmochim. Acta

Chem. Geol.

Quat. Sci. Rev.

Geochem. Cosmochim. Acta

Geochem. Cosmochim. Acta

Quat. Sci. Rev.

Variable winter moisture in the southwestern United States linked to rapid glacial climate shifts

Nat. Geosci.

Extrapolar climate reversal during the last deglaciation

Sci. Rep.

Pollen-based continental climate reconstructions at 6 and 21 ka: a global synthesis

Clim. Dynam.

Synoptic and mesoscale controls on the isotopic composition of precipitation in the western United States

Clim. Dynam.

Limnological and climatic environments at Upper Klamath Lake, Oregon during the past 45000 years

J. Paleolimnol.

Environment and paleolimnology of Owens Lake, California: a record of climate and hydrology for the past 50,000 years

The Asian monsoon over the past 640,000 years and ice age terminations

Nature

Comparative study of the kinetics and mechanisms of dissolution of carbonate minerals

Chem. Geol.

Petrography and origin of permian McCloud limestone of northern California

J. Sediment. Petrol.

North-south precipitation patterns in western North America on annual to decadal timescales

J. Clim.

Fifty-two years of “pineapple express” storms across the west coast of North America. U.S. Geological survey, scripps institution of oceanography for the California energy commission

δ¹⁸O and δ¹³C