Skip to main content
U.S. flag

An official website of the United States government

Get to Know a Scientist Emeritus-Marith Reheis

This is the sixth in a series of Get to Know posts highlighting and celebrating the contributions of exemplary Scientists Emeriti. Their work, experience, and contributions are essential to the mission of the USGS.

After seven years of retirement, Marith Reheis remains an active and productive Scientist Emeritus at the Geosciences and Environmental Change Science Center. She continues to regularly publish important work on pluvial lakes and paleohydrologic environments that provides valuable contributions to paleoclimatology and quaternary science, and works with collaborators in the USGS and beyond. She also helps to mentor and guide younger geologists in the USGS, sharing her valuable experience and advice. She has received repeated accolades for her distinguished career and was recognized in a 2018 report as one of only six women in the USGS to have achieved the designation of senior scientist for her exceptional work. Marith has been a leader and a pioneer for women scientists at our center and across the USGS, and her ongoing work as both a scientist and a mentor are significant contributions.

Lara E. Douglas
Director, Geosciences and Environmental Change Science Center


Marith Reheis sampling desert dust, Mohave Desert, California.
Scientist Emeritus Marith Reheis sampling desert dust in the Mohave Desert, California.


What attracted or brought you to work for USGS in the first place?

Didn’t everyone want to work for the USGS? It was 1974; I was finishing up my master’s degree, was tired of being a student and wanted a job. The USGS was hiring into the Conservation Division mapping coal fields. I was hired as a full-time permanent employee and stayed in that position for 4.5 years. I worked in the area of a little town called Meeker in the western part of Colorado. It gave me a good opportunity to learn how to do field mapping and operate independently.

How long did you work at USGS before you retired and how long have you been an Emeritus?

About 38 years. Some of that was part-time when I went back to get a PhD. I became an Emeritus right when I retired and have been in the Emeritus Program for seven years.

What was your last title/position at USGS before you retired and became an Emeritus?

I was a Senior Scientist and Research Geologist.

What Science Center do you answer to as an Emeritus?

The Geosciences and Environmental Change Science Center in Denver, Colorado.

What are you most proud of during your career with the USGS? OR describe a highlight of your career.

There are two things:

The first is that a large part of my career has been sampling, analyzing, and publishing on modern dust in the western U.S. This work led into a huge, multi-collaborator effort to raise awareness of the importance of aeolian dust in the atmosphere and on the surface of the earth; in particular, how aeolian dust contributes to soils, plant nutrition, fertility, etc.

The other big thing was a result of coincidences and a lot of field work. Beginning in 1995, I studied pluvial periods of the Pleistocene. When glaciers were big, there were really big lakes in the internally drained valleys of the Great Basin. For example, Lake Bonneville and Lake Lahontan were once huge lakes where now the remnant Great Salt Lake in Utah, and Pyramid Lake and Walker Lake in Nevada remain. Many previous studies had focused mainly on the last high lake levels, about 15,000-20,000 years ago. I found that there was good evidence in exposed sediments that lakes were much bigger and reached much higher levels before that time and were especially large about 600,000 years ago. What happened is that these big lakes overflowed and discharged to other basins, which resulted in the construction of a river system that hadn’t been there before. I collaborated with biologists who studied fish, snails, etc. These overflowing big lakes gave opportunities for the critters to move around, which helped biologists explain why fish species were closely related in basins that, before this discovery, were thought to have no connection to each other.

What led you to decide to become an Emeritus?

I wasn’t done! Honestly it was wonderful to become a ST, but at that point, I took on more responsibilities and, in some ways, felt that I was going to have to work even harder to justify the salary. Plus, my husband was slipping into early dementia and we wanted to travel more. Although I wasn’t done with my work, I wanted to do it at my own pace and my own time. There were projects that never got completed and I have been able to do more field work and get them done.

Marith Reheis digging a soil pit in Fish Lake Valley, Nevada.
Marith Reheis digging a soil pit in Fish Lake Valley, Nevada.

What exciting research or service activities are you currently working on and what are you planning for the near future?

One of my last employed big projects was on the Mojave River in southern California, studying the climatic history recorded in the sediments of Lake Manix that the river once fed. I’m finishing up one last publication on that subject. I’m working with a collaborator at San Francisco State on pluvial Lake Manly in Death Valley and thinking about enlisting Dan Muhs (Research Geologist with the Geosciences and Environmental Change Science Center) to help me write up a paper on the strontium isotopic composition of modern desert dust to pin down the source of the dust. Data were accumulated years ago.

What do you enjoy and appreciate the most about being an Emeritus?

I can keep networking with friends and colleagues. I have many close friends in the USGS and at universities. Also, I can do field work and get things done at my own pace.

I love doing field work, I’m good at it. I have a knack for looking at the landscape and seeing things that others may not notice. Back in my early USGS days, I was doing a lot of surficial geologic mapping. We did all of our initial interpretation and compilations using stereo pairs of aerial photographs, mapping on the photos and transferring those data onto a topo map. Seeing things in stereo, then field checking the interpretations played a big role in helping achieve that big picture view.

What type of mentoring or outreach activities do you currently undertake as an Emeritus?

I participate in a local scientific society called the Colorado Scientific Society. I am also a regular attendee on field trips with the “Friends of the Pleistocene.” I give talks and participate in field trips (of course, they are all virtual right now). There are lots of students on those trips that I interact with, help with ideas, and recommend thesis projects.

I also have coworkers and colleagues who ask for advice and expertise. For example, I help identify the type of sediment or deposit in core samples. I often get invited to go to the field with someone to contribute my perspective. I didn’t have this when I was hired in 1974—there wasn’t much mentoring in my group, at least for females. I was assigned to map a quadrangle and it was sink or swim. When I was hired everyone worked in the field. I was issued a piece-of-junk field vehicle, hired an assistant (who didn’t really work out), and went to the field. Others were mapping in northwest  Colorado near me, but in different areas from where I was assigned to work. I spent five days with them looking at rocks and sediments, and they made sure I knew how to measure a section and that was about it. The first couple months were hard.

What are/were the most important decisions you made as a research scientist for your organization?

Persisting in dust and its behavior on the landscape when I had no funding to do it. I was re-hired after my PhD to work on the Yucca Mountain site, a nuclear waste repository in Nevada. There was a group of soils experts trying to use soils to estimate ages of landforms that might have been offset by faults. The concern was that there may be earthquake faults around the repository. I had experience in dust, so I got deputized to figure out a way to sample modern dust on a regular basis, then apply analyses of samples to the soil study. I put together a network of about 50 to 60 dust traps that stretched all the way from the Los Angeles area to the Nevada/Utah border, and from Mexico to Central Nevada. It was an enormous area to deploy and sample. Initial results were interesting, surprising, and useful. It became important to me to keep going so I persisted, even though funding collapsed in 1989. I still managed to collect samples while I was out on other trips. Interestingly, a few years later, lots of people got really excited about dust for a number of reasons including wind erosion, desertification, and an increase in satellite technology that allowed us to see where dust was crossing oceans.

The Gilbert Fellowship was a special pot of money for USGS geologists who had a bright idea that could not be funded through normal programmatic means. They only awarded one or two a year, and I got one in 1995. It was a proposal to look at tilting across the Lake Lahontan Basin to see if the entire basin was tilted toward the north, perhaps due to the passage of the Yellowstone hotspot. I had three months of field work funded; later, it became interesting enough to enough people that they gave me more money through the Climate Program. I got the initial funding for the same year that the reduction in force  happened so I was hardly in the office during that bad time. I began to see that there had been no tilting, but there was evidence of higher lake levels in many basins. One day I stretched out 2-degree sheets (shorthand for 1:250,000 scale topographic maps) on a king size bed in a motel room and let my eyes roam around the map and inspiration hit me that it was these very high lakes that put together the Humboldt River! This realization then had to be fleshed out with a lot of collaborators on age dating (volcanic ashes, vertebrate fossils, and paleomagnetics).

Have you had any great career mentors, and if so, what made them great?

When I first started mapping, I didn’t really have mentors in the USGS. Peter Birkeland at the University of Colorado instilled his students with the ability to think deeply about problems and interpret landscapes. He was the main advisor for my dissertation work. In the USGS, 15 years older than I, was Ken Pierce, who was an inspiration in his leadership and in following intuition on new research. He is a Scientist Emeritus in Bozeman, Montana and works in Yellowstone.

Marith Reheis, rafting in the Green River, Utah: Picture taken by Corey Lawrence, USGS Research Geologist at the GECSC.
Marith Reheis, rafting in the Green River, Utah: Picture taken by Corey Lawrence, USGS Research Geologist at the GECSC.

What is your best advice for early and mid-career scientists?

Take every opportunity you can get to try new approaches and to reach out to colleagues and even total strangers to collaborate on things you might not ordinarily do as a part of your specific project. There are opportunities out there if you know how to grab them. People can come up with new and innovative ways to approach problems because they are collaborating with others. It can be intimidating to cold-call someone who is a stranger and ask to work with them, but it’s really important.

Where did you travel last, domestically or internationally?

In June of 2019, I went on a six-day raft trip on the Green River. It’s hard to get away from the modern world, but rafting is a good way to do it. Being able to unplug is important.

What’s the biggest risk you have ever taken?

Toward the end of 4.5 years in my first full-time permanent position, we were being ordered to spend more time calculating coal tonnages (how much coal might be able to be mined, etc.), and that was not what I was on board to do. I enjoyed mapping and compilation work, but I didn’t want to be turned into an economic calculator. I also met my husband and got married about then. I decided to go back to graduate school to study soils so I quit my permanent, full-time position and took a WaE (Work as Employed) temporary part-time position. Everybody thought I was crazy to quit but it worked out. In 1984, I finished a PhD in something that was important to the work that was being conducted on the Nevada Test Site, so within a year I was rehired again into a permanent, full-time position.

What resources or advice would you give someone going into a research position for the first time?

Serendipity plays a surprisingly big role in a long research career. Be open to opportunities and inspirations that might lead you to new directions diverging from the path you were following. You might encounter someone or something that will change your career path. I never dreamed that I would spend a whole career with dust. After 25 years, I was tired of it but the first 10-15 years were great.

Marith Reheis at the Grand Canyon, Arizona.
Marith Reheis at the Grand Canyon, Arizona.

Get Our News

These items are in the RSS feed format (Really Simple Syndication) based on categories such as topics, locations, and more. You can install and RSS reader browser extension, software, or use a third-party service to receive immediate news updates depending on the feed that you have added. If you click the feed links below, they may look strange because they are simply XML code. An RSS reader can easily read this code and push out a notification to you when something new is posted to our site.