Graham Harper Edwards, PhD

Graham Harper Edwards, PhD

he | him
geo/cosmo chemistry
geo/cosmo chronology
Assistant Professor (Fall 2024)

gedward1 at trinity.edu

Posts by Collection

outreach

portfolio

publications

Detecting the extent of ca. 1.1 Ga Midcontinent Rift plume heating using U-Pb thermochronology of the lower crust

G.H. Edwards and T. Blackburn
Geology, 2018       PDF       Web

We combine U-Pb thermochronology of rutile and apatite from middle-to-lower crustal xenoliths form an Attawapiskat kimberlite with paired crustal thermal and Pb-production diffusion models to ascertain the timescales of plume heating beneath the Superior Craton in midwestern Canada. Thermochronologic data are best fit by model simulations in which the Attawapiskat lithosphere experienced a ca. 1.1 Ga heating event triggered by partial lithosphere removal and mantle temperatures >200 °C in excess of that of ambient mantle, consistent with a model of ∼100 m.y. plume head residence beneath the Attawapiskat region.

Ice retreat in Wilkes Basin of East Antarctica during a warm interglacial

T. Blackburn, G.H. Edwards, S. Tulaczyk, M. Scudder, G. Piccione, B. Hallet, N. McLean, J.C. Zachos, B. Cheney, J.T. Babbe
Nature, 2020       PDF       Web

Press coverage in National Geographic
U-series isotopics of subglacial precipitates from beneath the East Antarctic Ice Sheet (EAIS) record an open-system event ca. 400,000 years ago in the subglacial Wilkes Basin. Our data and models support ice retreat and seawater incursion during this time, suggesting that the Pleistocene EAIS was not as stable as previously assumed. These findings bear important implications for future EAIS stability in a warming climate.

An early giant planet instability recorded in asteroidal meteorites

G.H. Edwards, C.B. Keller, E.R. Newton, C.W. Stewart
Nature Astronomy, 2024       Web       Preprint       Code

We use a Bayesian statistical code to constrain the timescales of giant planet migration and asteroid belt bombardment in the early solar system. Our results associate giant planet migration with the dissipation of the gaseous protoplanetary disk.
I was invited to write a more broadly accessible Research Briefing that summarizes the relevance and main conclusions of our study.
The preprint was also summarized by Astrobites, and I was quoted in two recent articles on the topic of giant planet migration in Science Magazine and Sky & Telescope.

Uranium-series isotopes as tracers of physical and chemical weathering in glacial sediments from Taylor Valley, Antarctica

G.H. Edwards, G.G. Piccione, T. Blackburn, S. Tulaczyk
Chemical Geology, 2025       Web       Code       Data

Uranium series isotopes are sensitive tracers of both chemical and physical weathering. We report U-series data from fine-grained sediments form Taylor Valley, Antarctica that were deposited over the course of the last million years. Using novel numerical techniques we interpret the coupled chemical-physical weathering histories and show that Taylor Glacier has been eroding into Taylor Valley over the course of the Pleistocene.

research

talks

teaching

Geologic Principles

Teaching Assistant, UC Santa Cruz, Earth & Planetary Sciences, 2018

Introductory Earth Science coarse covering the fundamentals of geosciences, with an emphasis on solid Earth topics.
Instructor: Prof. Terrence Blackburn.

Geochemistry of the Solar System

Teaching Assistant, UC Santa Cruz, Earth & Planetary Sciences, 2018

Overview of the meteorite record and the processes of solar system evolution and planetary formation from a geochemical perspective.
Instructors: Profs. Myriam Telus and Terrence Blackburn.

Principles of Field Geology

Teaching Assistant, UC Santa Cruz, Earth & Planetary Sciences, 2019

Field-based course focusing on fundamental geologic principles, field skills, and the creation of geologic maps.
Instructor: Dr. Hilde Schwartz

Evolution of Earth

Teaching Assistant, UC Santa Cruz, Earth & Planetary Sciences, 2020

Overview of Earth system processes and history for Earth science majors.
Instructors: Profs. Paul Koch and Terrence Blackburn.

Measuring Earth’s 4.5 Billion-Year History

Teaching Assistant, UC Santa Cruz, Earth & Planetary Sciences, 2021

Radiogenic and stable isotope geochemistry: isotopic systems and their applications in the Earth sciences.
Instructors: Profs. Terrence Blackburn and Jim Zachos.

Exploring Our Universe

Lecturer (Instructor of Record), Dartmouth College, Physics & Astronomy, 2023

Introductory astronomy course covering the fundamentals of astronomy with an emphasis on the diversity of astronomical objects and how we have described them with observational techniques. (Co-instructors: Prof. Elisabeth R. Newton, Prof. Aaron L. Dotter).

The Stretch

Co-Instructor, Dartmouth College, Earth Sciences, 2023

Glaciology, paleoclimate, and surface mapping segment (Oct. 15–23) of a full-term field geology course. Field sites in the Eastern Sierra Nevada of California, including Long Valley, Owens Valley, and the Mono Basin. Co-instructor: Prof. Meredith Kelly)

Exploring Our Solar System

Lecturer (Instructor of Record), Dartmouth College, Physics & Astronomy, 2024

Introductory astronomy course covering the fundamentals of astronomy and planetary science.

Global Climate Change

Professor, Trinity University, Earth & Environmental Geosciences, 2024

Advanced climate science and history course.