About

Arjun Heimsath is a professor in the School of Earth and Space Exploration at Arizona State University with affiliations to the Center for Biodiversity Outcomes, Water Institute, Global Drylands Center, and Global Futures Scientists and Scholars. He grew up in the foothills of the Indian Himalaya and the Hill Country of Texas, experiences that fueled his passion for understanding Earth's surface processes. His early work as a Peace Corps water development engineer on the coast of Kenya led him to focus on environmental science, which he further pursued in the Nepal Himalaya by quantifying differences between human and natural erosion processes. Through this work, he discovered the field of geomorphology and concentrated his research on Earth's critical zone, the thin skin of the Earth's surface that supports human life. His main research interests include soil and water sustainability, geomorphology, tectonic geomorphology, carbon sequestration, exposure-age dating, glacial geomorphology, and human impacts on landscapes.

Research topics

• Paleontology
• Geography
• Ecology
• Geology
• Geomorphology
• Physical geography
• Oceanography
• Biology
• Geochemistry
• Soil science
• Environmental science
• Earth science

Selected publications

• Quantifying Geomorphic Processes and Rates of Landscape Evolution

  Abstracts with programs - Geological Society of America · 2025-01-01

  article1st authorCorresponding
  PublisherDOI

• Relict soil evidence for post-Miocene aridification in the Atacama Desert of South America

  Geological Society of America Bulletin · 2024-07-31 · 1 citations

  article

  Abstract Deep exposures of soil profiles on Miocene or Mio-Pliocene alluvial deposits were studied along a 500 km N-S transect in the Atacama Desert. These ancient deposits, with excellent surface preservation, now stand many meters above a broad incised Plio-Pleistocene alluvial terrain. Total geochemical analyses and mass balance calculations allowed the establishment of elemental gains, losses, and redistribution in the soils. From north to south (presently hyperarid to arid), the ancient soils reveal an increase in losses of rock-forming elements (Si, Al, Fe, K, Mg). Additionally, rare earth elements (REE) show losses with increasing southerly latitude and systematic patterns with soil depth. Some REEs appear to be unique chemical tracers of exogenous dust and aerosol additions to the soils. The removal of major elements and REEs is impossible in the present climate (one of salt and dust accumulation), revealing that for a significant period following the deposition of the alluvium, soils were exposed to rainfall, chemical weathering, and mass loss—with a geographical pattern that mirrors the present rainfall gradient in the region. Following the cessation of weathering, the pre-weathered soils have undergone enormous dust and salt accumulations, with the rates and types of salt accumulation consistent with latitude: (1) carbonate in the south and (2) sulfate, chlorides, and nitrates to the north. The quantity, and apparent rates, of salt accumulation have a strong latitudinal trend. Isotopes of sulfate have predictable depth patterns based on isotope fractionation via vertical reaction and transport. The relict hyperarid soils are geochemically similar to buried Miocene soils (ca. 10–9 Ma) in the region, but they differ from older Miocene soils, which formed in more humid conditions. The overall soil record for the Atacama Desert appears to be the product of changes in Pacific Ocean sea surface temperatures over time, and resulting changes in rainfall. The mid-Miocene was relatively humid based on buried soil chemistry and evidence of fluvial activity. The mid to late Miocene cooling (ca. 10–5.5 Ma) appears to have aridified the region based on paleosol soil chemistry. Pliocene to earliest Pleistocene conditions caused weathering of the relict soils examined here, and regional fluvial activity. Since the earliest Pleistocene, the region has largely experienced the accumulation of salts and, except for smaller scale oscillations (glacial-interglacial), has experienced protracted hyperaridity.

  PublisherDOI

• DUST INPUT TO REGOLITH AND CHEMICAL EROSION OF CARBONATE HILLSLOPES: A MASS BALANCE APPROACH

  Abstracts with programs - Geological Society of America · 2024-01-01

  article
  PublisherDOI

• CHARACTERIZING REGOLITH THICKNESS IN THE PINALEÑO MOUNTAINS, SE ARIZONA, USING SHALLOW SEISMIC REFRACTION

  Abstracts with programs - Geological Society of America · 2023-01-01

  articleSenior author
  PublisherDOI

• DISENTANGLING PRIMARY CONTROLS ON LANDSCAPE EVOLUTION OF THE NORTH-CENTRAL ANDES: NEW ¹⁰BE EROSION RATES FROM SOUTHERN PERU

  Abstracts with programs - Geological Society of America · 2023-01-01

  article
  PublisherDOI

• Isolating climatic, tectonic, and lithologic controls on mountain landscape evolution

  Science Advances · 2023 · 58 citations

  Senior authorCorresponding
  • Geology
  • Physical geography
  • Geomorphology

  , intrinsically assumes that climate is uniform. Consequently, its use where rainfall varies spatially undermines efforts to distinguish climate from tectonic and lithologic effects, can bias reference concavity estimates, and may ultimately lead to false impressions about rock uplift patterns and other environmental influences. Capturing climate is therefore a precondition to understanding mountain landscape evolution.

  PublisherDOI

• Controls on topography and erosion of the north-central Andes

  Geology · 2023-12-12 · 20 citations

  articleSenior author

  Abstract We present 17 new 10Be erosion rates from southern Peru sampled across an extreme orographic rainfall gradient. Using a rainfall-weighted variant of the normalized channel steepness index, ksnQ, we show that channel steepness values, and thus topography, are adjusted to spatially varying rainfall. Rocks with similar physical characteristics define distinct relationships between ksnQ and erosion rate (E), suggesting ksnQ is also resolving lithologic variations in erodibility. However, substantial uncertainty exists in parameters describing these relationships. By combining our new data with 38 published erosion rates from Peru and Bolivia, we collapse the range of compatible parameter values and resolve robust, nonlinear ksnQ–E relationships suggestive of important influences of erosional thresholds, rock properties, sediment characteristics, and temporal runoff variability. In contrast, neither climatic nor lithologic effects are clear using the traditional channel steepness metric, ksn. Our results highlight that accounting for spatial rainfall variations is essential for disentangling the multiple influences of climate, lithology, and tectonics common in mountain landscapes, which is a necessary first step toward greater understanding of how these landscapes evolve.

  PublisherDOI

• Hillslope Morphology Drives Variability of Detrital ¹⁰Be Erosion Rates in Steep Landscapes

  Geophysical Research Letters · 2023-08-28 · 11 citations

  articleOpen access

  Abstract The connection between topography and erosion rate is central to understanding landscape evolution and sediment hazards. However, investigation of this relationship in steep landscapes has been limited due to expectations of: (a) decoupling between erosion rate and “threshold” hillslope morphology; and (b) bias in detrital cosmogenic nuclide erosion rates due to deep‐seated landslides. Here we compile 120 new and published 10 Be erosion rates from catchments in the San Gabriel Mountains, California, and show that hillslope morphology and erosion rate are coupled for slopes approaching 50° due to progressive exposure of bare bedrock with increasing erosion rate. We find no evidence for drainage area dependence in 10 Be erosion rates in catchments as small as 0.09 km 2 , and we show that landslide deposits influence erosion rate estimates mainly by adding scatter. Our results highlight the potential and importance of sampling small catchments to better understand steep hillslope processes.

  PublisherOA PDFDOI

• The Mojave Section of the San Andreas Fault (California): 1. Shaping the Terrace Stratigraphy of Little Rock Creek Through the Competition Between Rapid Strike‐Slip Faulting and Lateral Stream Erosion Over the Last 40 k.y.

  Geochemistry Geophysics Geosystems · 2023-10-01 · 2 citations

  articleOpen accessSenior author

  Abstract To determine the post‐40 ka slip‐rate along the Mojave section of the San Andreas Fault (MSAF) we re‐analyze the sedimentary record preserved where Little Rock (LR) Creek flows across the fault. At this location, interaction between the northeast‐flowing stream and right‐lateral fault has resulted in the abandonment and preservation of 11 strath terraces and one paleo‐floodplain in the downstream trailing corner of the river, two of which are also preserved upstream to provide cross‐fault matches. A new model of fault‐induced river deflection, together with standard terrace riser restoration, yields strike‐slip displacements of 1,140 ± 160 m for the older terrace and 360 ± 70 m for the younger one. When combined with new 10 Be dating and reinterpretation of prior measurements the displaced terraces yield right‐lateral slip‐rates of 27.7 +6.9/−3.5 and 26.8 +3.4/−3.0 mm/yr over the last 23 k.y. and last 40 k.y., where uncertainties are at 95% credible intervals. These new rate determinations are consistent with independent late Holocene estimates, indicating that the long‐term rate of strain accumulation along the MSAF is relatively fast and does not vary significantly when averaged over timescales of 15–20 k.y. Using our new model of stream deflection, we find that the fluvial sequence was emplaced in two distinct periods, each characterized by a temporally stable but markedly different deflected river geometry. Each period coincides with a distinct stage of erosive power along LR Creek determined from independent paleoclimate proxies. Importantly, application of the new river‐deflection model allows strike‐slip displacements to be determined in the absence of upstream piercing points.

  PublisherOA PDFDOI

• Low variability runoff inhibits coupling of climate, tectonics, and topography in the Greater Caucasus

  Earth and Planetary Science Letters · 2022-04-01 · 25 citations

  articleOpen access
  PublisherOA PDFDOI

Recent grants

• CAREER: Quantifying Erosional Processes on Upland Landscapes

  NSF · $94k · 2008–2009

• Landscape Sensitivity to Changing Climate: Plio-Pleistocene Erosion and Sedimentation in SE Arizona

  NSF · $240k · 2011–2014

• Collaborative Research: Tectonics and Topography in the Transverse Ranges: Landscape Response to Rock Uplift Rate across the Transition from Soil-Mantled to Rocky Slopes

  NSF · $140k · 2005–2008

• QEIB: Collaborative Research: Erosional Removal and Redistribution of Soil Organic Carbon In Upland Ecosystems

  NSF · $218k · 2002–2006

• Collaborative Research: Tectonics and Topography in the Transverse Ranges: Landscape Response to Rock Uplift Rate across the Transition from Soil-Mantled to Rocky Slopes

  NSF · $153k · 2007–2010

Frequent coauthors

• K. X. Whipple

  University of Arizona

  57 shared

• Ronald Amundson

  39 shared

• W. E. Dietrich

  Planetary Science Institute

  29 shared

• Roman A. DiBiase

  Pennsylvania State University

  21 shared

• Matthew Jungers

  19 shared

• James M. Kaste

  19 shared

• J. L. Dixon

  15 shared

• Kyungsoo Yoo

  14 shared

Education

• Ph.D., Geology

  University of California-Berkeley

  1999

• M.S., School of Forestry and Environmental Studies

  Yale University

  1993

• B.S., Mechanical Engineering (honors)

  Yale College

  1989