Eric Portenga

Hot Water Cascade on Arlington Lawn at Hot Springs National Park, taken at night. The tufa rocks above the spring are lit up.

Photo of Display Springs, a pool in the foreground being fed by two hot water springs in the hillside in the background.

Photo of six hot springs on a mowed lawn. Each is capped with a green lid and water is diverted to the nearby bathhouses.

A natural hot spring emerging from a mowed grassy hillslope behind Bathhouse Row at Hot Springs National Park. Abandoned buildings of the old Army and Navy Hospital are in the background.

The #HotSprings themselves were pretty cool, if not entirely picturesque. Most are capped to ensure Bathhouse Row has enough water. Water emerges out of the ground ~140°F! #Geology #NationalPark #EarthScience

View of Hot Springs, Arkansas, from the top of the observation tower on North Mountain looking towards West Mountain.

Steeply dipping beds of the Stanley Shale and Hot Springs sandstone exposed behind a parking lot in Hot Springs, Arkansas

Photo of me along the Sunset trail on West Mountain at Hot Springs National Park amidst some outcrops of novaculite, a type of cryptocrystalline quartz. It is erosion resistant and holds up the ridge line here

Looking north along the Sunset trail on West Mountain at Hot Springs National Park amidst some outcrops of novaculite, a type of cryptocrystalline quartz. It is erosion resistant and holds up the ridge line here

#Geomorphology Week is ending, and I was lucky enough to get down to #HotSprings #NationalPark where 4,000 yr heated #groundwater rises to Earth’s surface via the Hot Springs #Fault, part of the Ouachita Orogeny. Ridges here are held up by cryptocrystalline quartz of the Arkansas Novaculite #Geology

Shaded relief from LiDAR imagery of the area near the Eastern Michigan University Fish Lake Environmental Field Station (black outline).

An elongate kettle bog in the woods in winter. The water is frozen. Some trees have fallen across the bog. Location is the Eastern Michigan University Fish Lake Environmental Field Station near Lapeer, Michigan.

A small circular vernal pool at the bottom of a kettle in the woods in winter. The water is frozen. Location is the Eastern Michigan University Fish Lake Environmental Field Station near Lapeer, Michigan.

Got my #GlacialGeology course out to the #EMU Fish Lake Environmental Field Station near Lapeer #Michigan last Friday. It's mapped as end #moraine, but jury's out. Lots of glaciofluval seds, #kettles, and a nearby #esker. More work to do! #Geology #EarthScience #GreatLakes

Been ages! First things first. This week Stacy Tchorzynski, Director of #Archaeology at @michigandnr.bsky.social and the #Michigan History Center visited #EMU to talk about overlaps between Archaeology and #Geology and #EarthScience! Great turn out for the #NSF supported #GLEEClubEMU series.

Lab* 🤦

Bench top setup for a Frantz mineral separator

Chipmunk jaw crusher and Pulverizer on a bench top in a lab setting

Lap updates update! Just in time for the holidays we’ve finally unpacked and set up our new Chipmunk Crusher, Pulverizer, and Frantz! A new year will bring new mineral separation capabilities to EMU’s #Geology program. #EarthScience #Research

Challenges in developing a Schmidt hammer exposure‐age dating calibration curve from glacial erratics in the North American Great Lakes Against expectations, mean Schmidt hammer R-values measured on 34 glacial erratics across six moraines in Wisconsin exhibit no meaningful relationship to independently determined cosmogenic 10Be expo...

New Paper Alert! 🚨 2nd of 2 #UndergraduateResearch studies led by a past #EMU #Geology student! Schmidt Hammer dating didn't work for us in the #GreatLakes. We muse on why we think our 'negative results' are still useful! #EarthScience #Glacial #Geochronology
onlinelibrary.wiley.com/doi/10.1002/...

Undergrads student standing behind a large glacial erratic in the woods

Top-view of a glacial erratic all chalked up in preparation for measurement

Undergrad student making Schmidt hammer measurements on top of the glacial erratic

Clear skies for the last few days means we can get out to do some #undergraduate #research on the Sturgis Moraine #Michigan, seeing whether we can reorient displaced #glacialerratics with a Schmidt Hammer 🪨 🔨 🧐

#geosciences #earthscience #geology #geomorphology #GreatLakes #EMU

We made it! Today is the first day of the Great Lakes Earth Exchange guest speaker program at #EMU. 🥳 Ph.D. Candidate Ashley Scott from Western Michigan University is the first official member of the #GLEEClubEMU. Come hear her talk about Dolomite 🪨 at 2PM in 111 Strong Hall! #Geology #EarthScience

I mean, has anyone ever even seen a new Frantz? Every one I’ve used is like yours! 😂

Wooden Crate showing the SG Frantz company logo. Inside is a giant magnet

Coming soon to #EMU, magnetic mineral separation!
🪨 🧲 ✨😍

#Geology
#EarthScience
#Magnets
#Research

A student using an iPad to create a 3D scan of a glacial erratic in a forested setting

Got into the field this week for a new student project who is creating 3D scans of dated erratics and measuring them to see if there are metrics that help distinguish between moved and unmoved rocks!
#MichiganErratics
#GreatLakes
#GlacialGeology
#EarthScience
#Geology
#UndergraduateReeesrch
#EMU

CAS Newsletter STUDENT HIGHLIGHTS

The October #EasternMichiganUniversity College of Arts and Sciences October Newsletter is chockablock with updates on #Geography #EarthScience and #Archaeology research and work being done by me and my colleagues WITH our students.

#GreatLakes #MichiganErratics

sites.google.com/emich.edu/ca...

Poster for the 2025-2026 line-up for the Great Lakes Earth Exchange speaker series at Eastern Michigan University. A QR code links to the a Geomorphology webpage with more information.

SO excited to announce the inaugural line-up of the #NSF funded Great Lakes #Earth Exchange speaker series (aka the #GLEEClubEMU) at #EasternMichiganUniversity. We've got talks on dolomitization, #groundwater modelling, #archaeology, and #GreatLakes water #chemistry. All are welcome to attend!

@geodesaurus.bsky.social the Haunted Hydrology ologies episode was awesome! Heard your mother’s name mentioned, and was like, that’s familiar. Then it clicked, an Eastern Michigan University geo link! Thanks for representing all us Geos of the #GreatLakes!

After 40 years and $84M in cleanup, Muskegon Lake comes off toxic list Federal, state and local officials gathered to announce the formal delisting of Muskegon Lake from the Area of Concern program.

Very proud of my hometown! #Muskegon and west #Michigan are hidden gems of our region! #GreatLakes

www.mlive.com/environment/...

Geomorphology @ EMU - Projects Laurentide Ice Sheet Retreat from the Great Lakes Region, USA

Learned last week that EMU invites creation of Faculty research pages via Google Sites, so I had a go at creating a new page for all things #Geomorphology at #EasternMichiganUniversity (linking to the #Research page since the home page is my face). Updates ongoing

sites.google.com/emich.edu/ge...

That feeling of hitting "Submit" on a revised manuscript after Reviewers suggest Minor Revisions 😎

More details soon!

#Geology #Geomorphology #EarthScience #QuaternaryGeology #Research

A sieve shaker, rock jaw crusher, and gravel plate grinder still strapped to their shipping pallets in a geology lab space

The #EMU #EarthScience Support #Laboratory is getting a makeover! Unboxed our new jaw crusher, plate grinder, and ro-tap sieve shakers today! Soon, #geology faculty will be able to do mineral separation in house! Just waiting on the magnetic separator 🧲

🪨🪨🪨

The 1954 Prospect Point Rockfall at Niagara Falls Amazing archive footage on Youtube showing the 1954 Prospect Point Rockfall at Niagara Falls in USA, which had a mass of 168,000 tonnes

Just learned about the 1954 Prospect Point #Rockfall at #NiagaraFalls. Amazing video footage of the rockfall as it occurred, too. Caused by dolostone dissolution over time. Will have to incorporate into my #Geomorphology course this fall.

blogs.agu.org/landslideblo...

Amazing! What do you attribute that growth to? Any suggestions for programs trying to improve enrolments?

Announcement expected to lock in long-awaited Great Koala National Park The long-touted Great Koala National Park is set to become a reality in New South Wales, protecting koala populations and other threatened species in the state's mid-north.

Having grown to love #Australia during my time there in grad school, this is such good news!

Protected koalas? ✅
Cultural heritage led by Aboriginal rangers? ✅

Such great news! The world needs more new #NationalParks

🐨 🐨 🐨

www.abc.net.au/news/2025-09...

Geology professor standing behind the Eastern Michigan University booth at Ypsilanti Community High School STEM night

Table top rock cycle matching activity

Baggies of crushed jolly rancher candy as stand-ins for sediment

Printout poster map of the Quaternary Geology of Washtenaw County, Michigan

Brave the wind, and come on down! Check out the #EMU #Geography and #Geology Department table at #STEM Night at #Ypsilanti Community High School! See if you can complete the Rock Cycle, make jolly rancher stratigraphy, and put a 📍 on the Quaternary Map of #Washtenaw County! #EarthScience

Portrait photo of beagle-lab mix sitting amongst leafy garden

Beagle-lab mix in the woods sniffing around a glacial erratic

Happy #InternationalDogDay to Max, our derpy #dog, lover of #LakeMichigan, and occasional #fieldwork assistant. Unfortunately, he doesn’t have a good nose for finding #MichiganErratics

A former #EMU student doing #undergraduate #research worked with a massive SH and 10Be dataset from #erratics in #Wisconsin to construct a SH exposure calibration curve for the #GreatLakes region, but we ended up with a “negative result” dataset…currently in review. Hope to have it published soon!

When Schmidt Hammer data are paired with #10Be exposure ages for #rocks, a calibration curve can be made. Ideally, Schmidt Hammer measurements can then be used to estimate rock exposure ages quickly and at cost. #geochronology

Large granite boulder positioned on a leafy forest floor. Moss is growing on one side and there is a series of small dots/markings on the boulder surface in a grid pattern

No, I’m not testing #MichiganErratics for allergies. Dots are #SchmidtHammer measurements that reveal the relative hardness of #rock surfaces. Strong rock ➡️ short exposure; weak rock ➡️ long exposure. #geomorphology #geology #geochronology #GreatLakes

Rock Looked Way Cooler Wet

Rock Looked Way Cooler Wet

Surface of a glacial erratic with a scale bar, sample ID sign, and a steel chisel bent in half

Surface of a glacial erratic with three evenly spaced cuts in the rock, which looks like Wolverine from the X-men was here

When the going gets tough sampling super hard #rocks and you bend a solid steel chisel, you know it is time to call in help from #Wolverine! #MichiganErratics

#geology #earthscience #geomorphology #fieldwork #research #icesheet #Quaternaryscience #Michigan #GreatLakes

Large boulders moved by farmers to a rock pile at the edge of a forest along with a rusty old car

Been back out in the field this week collecting nearly the rest of samples needed to date the Port Huron Moraine built by the Saginaw Lobe of the Laurentide #IceSheet. Hunting for #MichiganErratics in the “Thumb” of #Michigan has been hard because of centuries of farming and other land use