Donnel Foster Hewett Lectures

2019-2020 D. Foster Hewett Lecture Series

November 7th and 8th, 2019

Dawn of our modern world: Earth systems in the Neoproterozoic

The Neoproterozoic, an interval extending from about 1000 to 540 millions years ago, saw profound changes that set the stage for our modern planet Earth. It seems that by the Neoproterozoic parts of the solid Earth was experiencing more modern plate-tectonic activity, but surface processes, and feedbacks between the solid Earth, atmosphere, and the primitive biosphere were likely very different. The time span saw the extreme global glaciation events called Snowball Earth and the development of multicellular life, and the Neoproterozoic ended with the remarkable Cambrian Explosion in biological diversity. Big questions about this time period include what the links between Earth systems were like, and whether there were connections and even feedbacks between widespread deep erosion, snowball Earth, and evolution of a more modern biosphere.
This year’s Donnel Foster Hewett Symposium brings together four experts who will offer different perspectives on the Neoproterozoic, Kristin Bergmann from MIT, Willy Guenthner from Illinois, Brenhin Keller from Dartmouth, and Francis MacDonald from Santa Barbara. There will be a public lecture at 7 pm on Thursday, 7 November, and four talks and discussions from 10am to 4 pm on Friday, 8 November. The public is invited to all these talks. 
Detailed schedule
303 Whitaker, 7:30 to 9:00
The Neoproterozoic roots of the modern Earth system
Brenhin Keller (Dartmouth College)
101 STEPS Building, 10:00 to 4:15
10 to 10:15
Opening remarks
10:15 to 11:15
Climate extremes at the dawn of animal life
Kristin Bergmann (MIT)
11:15 to 12:15
In search of lost time: Constraints on Neoproterozoic exhumation of the Great Unconformity from deep-time thermochronology
Willy Guenthner (University of Illinois at Urbana-Champaign) 
2:15 to 1:30
Lunch break
1:30 to 2:30
The initiation of Snowball Earth 
Francis Macdonald (UC Santa Barbara)
2:30 to 3:30
A Neoproterozoic glacial origin of the Great Unconformity
Brenhin Keller (Dartmouth College)
  3:30 to 4:15
Panel discussion

The Great Unconformity is a widespread gap in the rock record that represents nearly one billion years of missing time. The example shown here is from the Needle Mountains of Colorado (Keller et al, 2019, PNAS, 116: 1136-1145).


Contact Prof. Peter Zeitler (, 610-758-3671) for additional details or answers to questions.