Sedimentologist, Stratigrapher, Geomorphologist

 

I study modern sedimentary systems and the record they leave behind.

 

Classically trained across the geological playground of Utah, I then earned my PhD conducting quantitative analysis of modern and ancient systems. I’m currently conducting paleohydraulic reconstructions of ancient rivers before the evolution of vegetation, and characterizing the morphodynamics of these ancient systems.

Pre-vegetation Rivers

Most rivers on earth are accompanied by thick corridors of vegetation, called riparian zones. To understand what vegetation really contributes to river channel stability, I am studying how rivers behave in the absence of plant life. To do this, I’m conducting flume experiments and examining ancient river sediments in the Scottish Highlands that were deposited before land plants evolved more than 400 million years ago.

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Upper Applecross Formation, Torridon, Scotland, UK

Upper Applecross Formation, Torridon, Scotland, UK

Actively meandering, single-thread flow first achieved in a flume study by Peakall et al. (2007).

Actively meandering, single-thread flow first achieved in a flume study by Peakall et al. (2007).

The Amargosa River, located in Death Valley, CA, is a rare example of a modern, vegetation-free river. From Ielpi et al. (2020).

The Amargosa River, located in Death Valley, CA, is a rare example of a modern, vegetation-free river. From Ielpi et al. (2020).

River Avulsion Dynamics

While we often think of rivers as dependable, fixed features of the landscape, in some circumstances they can jump their banks and reposition themselves across the floodplain. In some cases, this natural diversion, or avulsion, proceeds quickly and discretely, jumping into a nearby channel. In other cases, they occur through widespread flooding and disturbance to the surrounding floodplain. I study these phenomena to explore what controls different behavior, or styles.

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An example of an avulsion in Venezuela. This braided reach of river, hosting multiple channel threads, switched location from the upper path to the lower path, in what we term annexation. Flow is from the left to right.

An example of an avulsion in Venezuela. This braided reach of river, hosting multiple channel threads, switched location from the upper path to the lower path, in what we term annexation. Flow is from the left to right.

The same river in Venezuela, 60 km downstream. The river has transitioned into a single-thread, meandering channel. Here, another avulsion demonstrates a spreading network of new channels and flooding, in a process we term progradation. Flow is from

The same river in Venezuela, 60 km downstream. The river has transitioned into a single-thread, meandering channel. Here, another avulsion demonstrates a spreading network of new channels and flooding, in a process we term progradation. Flow is from left to right.

Dryland Sedimentary Environments

The Jurassic Entrada Sandstone is best known for it’s star role in Arches National Park, where thick deposits of ancient dunes erode into dramatic fins and dunes. I study the eastern extent of this formation, where it demonstrates a very different lithology- ephemeral lakes, or playas, and dryland river deltas, called terminal splays, form the bulk of the strata. These deposits erode into whimsical columns and boulders that fill the aptly named Goblin Valley .

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Eastern flank of the San Rafael Swell, Central UT. Visible formations from bottom up: Carmel Fm., Entrada Fm., Summerville Fm., Morrison Fm., Cedar Mountain Fm., Mancos Shale, Mesa Verde Group, North Horn Fm.