Five Years of Uŋčí Makhá Park

I've been doing some paleo events concerning hometown Mississippi National River & Recreation Area, giving me the opportunity to revisit some places. While doing this I realized A) I'd been visiting Uŋčí Makhá Park for almost exactly 5 years, and B) I'd inadvertently been doing an unplanned but reasonably effective version of repeat monitoring of specific fossils (in other words, I kept taking pictures of the same things). Previously I'd commented on how fossils had gotten along over the winter of 2022–2023. Now we can see how some have been fairing over four or five years of photographs. First, though, it's instructive to see how the overall setting has changed. Here's the south part of the "quarry" at the end of October in 2022, a few months after the park opened, photo facing south:

Here it is at the end of October, 2026:

Two things stand out (well, three: yes, I was standing at about the same point but took the photos at different angles). First, vegetation is filling in. Second, notice the outcrop wall on the left. In 2026, it's noticeably less clean. The slope here rises to the east (left), so groundwater is draining through the rocks on that side. Similarly, here's the north part of the "quarry" in 2022, again looking south:

And in 2026:

My placement wasn't as precise (since I didn't know I was doing repeat photography), but again, more vegetation and more gunk on the east wall. Now let's see some fossils. First is a bivalve steinkern, first photographed in November 2022:

A photo taken in May 2023 shows it about the same. By October 2024, though, something is definitely different:

A crack has developed, cutting through the margin of the fossil. Note also that the "shelf" just above it in the picture does not look to be as firmly attached. Now let's go to October 2026:

The setting is radically different. The "shelf" is gone (that's where the scale bar is). The block the fossil is on is crumbling; in fact, it was falling out when I got there, and I pushed it back in to take the photo. I would not be surprised if it falls out over the winter, making this the final photo I get of it. Next, let's look at a cheek spine from an Isotelus. Here it is in May 2023:

Here it is in September 2024. Pretty similar, but note the point of the spine:  

It's slightly damaged, appearing to have flaked away a bit. Now here it is in October 2026:

Fortunately, it's about the same. Finally, here are some photos of an enigmatic feature I just call a "potato chip". Here it is in May 2023:

Incidentally, I'm happy to take suggestions! It looks like the outer surface of some nautiloids, although if that's the case where's the rest of it? Is it just a fragment? Anyway, here it is in September 2024:

Like the bivalve, a large crack has developed (and please forgive the different placement of the scale bar. Like I said, this wasn't intentional monitoring). How is it in October 2026?

The crack has gotten wider, although the fossil itself is in about the same condition. We'll see if it goes as far as the bivalve in the next year or two.

All three fossils share a piece of timing: damage of some kind appeared between May of 2023 and September of 2024. The obvious suspect is the second winter of exposure, 2023–2024, although unfortunately my photographic interval isn't fine enough to say for sure. (I have dozens of photos from April 2023, but for some reason did not photograph these fossils.) It's interesting that additional changes have not been as notable; further damage has primarily been "improvements" on the 2023–2024 damage.

I'm rather pleased with this exercise. I don't often think of MNRRA in terms of paleontological monitoring; things come and go so quickly here from the Decorah, and, well, sometimes you don't think of the things at home the same way you think of things at places you have to travel to get to. Completely out of nowhere, whoever it was who decided to daylight Hidden Falls Creek this way has laid a beautiful monitoring case right in my lap, and it only took me five years of puttering around to realize it.

If you've gotten through all this and are weary of Platteville invertebrates, the fall 2026 issue of Park Paleontology News is up. Go check it out!

Compact Thescelosaurus Year Eleven

Here we are, time again for the annual check-in with The Compact Thescelosaurus. Last year, you may recall, Cretaceous crocodylomorphs joined the crocodylomorph tab. At the time, I knew I was going to go into the Cenozoic, but wasn't sure how far. In the end I opted to cover the entire Paleogene (Paleocene, Eocene, and Oligocene). This proved to be mostly members of modern groups. In fact, some of the species are assigned to living genera, although in most cases it's pretty sure that the assignment was a mistake (hence the many names in quotation marks).

And we add most of the Science Museum's crocs, including the Gavialosuchus/Thecachampsa carolinensis.

Indiana in St. Paul

We've talked about the hobby of observing building stone before. It combines geology, architecture, and history, you can get out for a walk, and it's usually pretty cheap. Anyone who's geologically inclined has probably found themselves casting an appraising glance at a building with stonework at least once. If you make a habit of it, some kinds of stone will begin to stand out, and if you put in some historical elbow grease you'll begin to pick up on non-geological aspects. For example, if you see this in St. Paul:

The stuff in the middle of the photo, roughly weathered.

That's Platteville, and you are probably looking at a very old structure. (Well, old in St. Paul terms.) Essentially, Platteville was used as building material until better and/or more fashionable stone became available with more money and better transportation. One of the first replacements was this:

Note the bedding.

If it looks familiar, that's because we just saw the Hinckley Sandstone a few weeks back. Those quarries up at Sandstone and Banning were sending rock for buildings like this. Another major material you'll see frequently is good old Kasota stone, or the Oneota Dolomite all dressed up.

In this case rather bioturbated-looking.

Kasota stone is a perennial favorite for stonework, and is still being quarried and widely distributed. There's another perennial favorite sedimentary rock that turns up quite a bit in St. Paul, but from farther afield. It's particularly well-represented in buildings dating from around the turn of the 20th century to World War II, and once you know what to look for, you'll see it all over. It's Indiana Limestone, the trade name for what geologists know as the Mississippian-age Salem Limestone. Indiana Limestone is off-white and looks like a sandstone from a distance, with the stone frequently given a corrugated surface. Once you eyeball up to it, you'll see that the grains are actually a fine hash of invertebrate fossils.

With occasional larger bits.

With corrugated appearance, and a couple of "larger" shells.

I haven't located any large areas of coarser fossils, as I've seen elsewhere, but there are occasional pockets. One of the more westerly columns at the entrance to Union Depot has some larger bits. Net-like bryozoans are particularly tell-tale; keep an eye out when passing a building with Indiana Limestone, and you might spot small net-like patches.

This one is pretty substantial for Indiana Limestone.

Some kind of shell in cross-section near the center?

In the vicinity of Kellogg, Union Depot, the Ramsey County Courthouse, the St. Paul Hotel, the Minnesota Building, and the InterContinental all have "outcrops" at eye level. Other buildings may have them higher up, but as with natural outcrops, if they're up above your head, you're not going to get much out of them.

It's Jaws! (or not.)

A good overall sample.

The Ramsey County Historical Society publishes a book, "Rocky Roots", composed of self-guided walking tours of St. Paul building stone. (The online purchase page doesn't seem to be working, unfortunately.) I have a copy of the 1978 edition, which is generally all right for what I'm looking for because most of the buildings that use Indiana limestone are older than that, so it's not so much missing new occurrences as losing old occurrences. (e.g., if you come across a 1978 copy and want to see the brachiopods that "add delicate winged-shell patterns" to the Vermont marble of Commercial State Bank on 5th and St. Peter, you'll also have to invest in a time machine, or just stand at the southeast corner of Landmark Plaza and imagine them.)

References

Kain, J., and P. Nelson. 2008. Rocky roots: geology and stone construction in downtown St. Paul. Ramsey County Historical Society, St. Paul.

Paleontology of Scotts Bluff National Monument

Those of us old enough to have attended elementary school circa 1985–1990 may remember the experience of successfully (or less-than-successfully) traversing The Oregon Trail. Although the game certainly included a great deal of content and detail, you can play as long as you like but you'll never find a trace of a fossil in it. The people who actually used the real Oregon Trail and its counterparts did find fossils, though. One such intersection of paleontology and human history is Scotts Bluff National Monument (SCBL), which you can read about in our freshly issued paleontological resource inventory (Shaffer et al. 2026).

A former exhibit at the monument's visitor center highlighted examples of journal records. Figure 2 in Shaffer et al. (2026).

SCBL is part of a small cluster of National Park Service units that document the middle Cenozoic of the northern Great Plains. The most famous of these is Badlands National Park and its White River Group, but of course there is also Agate Fossil Beds National Monument and the younger Arikaree Group. Niobrara National Scenic River we saw last year. Wind Cave National Park also has some White River Group outcrops, and Fort Laramie (another place in The Oregon Trail) of today's Fort Laramie National Historic Site sits among Arikaree Group strata and was used by O.C. Marsh as a base of operations. Another Trail landmark, Chimney Rock, is the focus of NPS-affiliate Chimney Rock National Historic Site as well as the source of type specimens for the bird Phasianus (now Archaeophasianus) mioceanus Shufeldt 1915 and the rodent Eumys brachyodus Wood 1937. SCBL fits quite neatly among this regional crowd, complementing some of them and partially filling the temporal and stratigraphic gap between the Early Oligocene of Badlands and the Early Miocene of Agate Fossil Beds.

Click to expand for the annotations. 120 years can make a difference! Figure 5 in Shaffer et al. (2026).

The new report includes a new stratigraphic column for the monument and a detailed discussion of the mammalian biostratigraphy. Stratigraphically the monument encompasses the Oligocene part of the White River Group (Brule Formation), the mid-Oligocene Gering Formation, and younger undivided strata of the Arikaree Group. The biostratigraphy and lithostratigraphy are not quite nailed down at the top, but there is reasonable (but not conclusive) evidence that it gets into the late Early Miocene (Hemingfordian).

And if you want the technical explanation for the previous image... Figure 7 in Shaffer et al. (2026).

What kinds of fossils have been found at the monument? The great majority with solid location information come from the Brule Formation, so if you're familiar with Badlands, Scotts Bluff won't seem terribly different. There are the inevitable turtles (observed by 19th century travelers), oreodonts, and nimravids, and a whole host of ungulates. (There are only so many ways to say "small, extinct, and deer-like". It's a bit like "hypsilophodont" for any small bipedal ornithischian.) The higher stratigraphic units have not been as profuse with vertebrate body fossils as the Brule, but they do all right with trace fossils. In fact, trace fossils are one of the monument's specialties. There are vertebrate burrows in the Brule about 0.3 meter (1 foot) across and up to 4 meters (13 feet) long. One is associated with a turtle specimen. Cross-sections of animal tracks can be seen in the Gering Formation, some of which may have been made by entelodonts. Root traces and invertebrate burrows are abundant in the undivided Arikaree Group (Shaffer et al. 2026).

A number of tracks can be seen in cross-section just above the pronounced break, and the underside of one is just peeking out a little right of center. Figure 12 in Shaffer et al. (2026).

Although the people traveling by Scotts Bluff did not have time to do much more than note fossils, the site and its geologic exposures attracted geological interest. As a result, there are substantial vintage collections from "Scotts Bluff" (regrettably little other provenance information at hand) at the American Museum of Natural History, Harvard's Museum of Comparative Zoology, the Smithsonian, and especially Yale's Peabody Museum of Natural History, which has probably the longest history. At least seven fossil taxa were named from specimens found at or in the vicinity of the bluff, although only four could still be considered in use. Despite the evident interest, a comprehensive description of the site's paleontology has not been prepared until now. Scotts Bluff National Monument can take its rightful place among the paleontological parks of the Great Plains.

References

Shaffer, A. B., E. Evanoff, E. Welsh, J. S. Tweet, and V. L. Santucci. 2026. Scotts Bluff National Monument: paleontological resource inventory (public version). Science Report NPS/SR—2026/504. National Park Service, Fort Collins, Colorado. https://doi.org/10.36967/2319364.

Shufeldt, R. W. 1915. Fossil birds in the Marsh Collection of Yale University. Transactions of the Connecticut Academy of Arts and Sciences 19: 1–110.

Wood, A. E. 1937. The mammalian fauna of the White River Oligocene. Part II. Rodentia. Transactions of the American Philosophical Society 28(2): 155–269.

Punchbowls and Mixing Bowls

Although amazing scenic geology is not usually considered one of the features of east-central Minnesota and west-central Wisconsin, this area has its surprises. For example, there are a few places that are known as "mixing bowls" or "punchbowls", sometimes with "Devil's" attached. The "bowl" part of the name can be a bit confusing at first if, like me, you think of a bowl or other enclosed depression. Rather, these sites are steep-sided short narrow gorges just off of larger drainage. At one time they were supplied with enough flowing water to carve a gorge, but this has now dwindled to practically nil. If you go above the bowl, you'll find the former streambed. The bowls form wonderful secluded glens. Some are easier to find (and more widely publicized!) than others. Here are three I've come across, all in western Wisconsin.

Seashells in the Salton Trough, 1775

Among the various types of National Park Service units are National Historic Trails. Many of these pass through fossiliferous areas, but stating that fossils are found on a given trail is not always easy. Unlike national parks and national monuments, where the NPS owns and manages parcels of land, the trails are not defined by boundaries, per se. In their absence, I like to look for reports of fossils made by users of the original trails, like the handful of fossils observed by Lewis and Clark, or John Strong Newberry's extensive description of the Santa Fe Trail. That at least shows a historical association.

Juan Bautista de Anza National Historic Trail, located in Arizona and California, recognizes the 1775–1776 expedition led by Juan Bautista de Anza to establish a Spanish presence in San Francisco Bay and an overland route to the area from greater New Spain, as the California coast was otherwise only accessible by water. If you're from the Southwest or have an interest in the Cenozoic paleontology of that area, you may have already recognized that name as part of California's Anza-Borrego Desert State Park, and you may have guessed where I'm going...

Anyway, one of the members of the expedition was Padre Pedro Font, a Franciscan missionary. Font was the expedition's chaplain, was responsible for taking latitudes, and also kept a diary (link to English translation). From this we can see that the expedition was not especially comfortable for him; a significant part of the trip he was ill with various maladies, and there were several bouts of bickering with his commander. (If someone asked you to lug around a psalterio and then never asked you to play it, or didn't give you access to the surveying tool you were supposed to be using, all while you were suffering from malarial fevers, you'd probably be annoyed too.) Also, of course, the reader should not expect that an 18th century missionary's first response to unfamiliar natives is going to be "These people are doing all right and we should certainly not try to change them in any way." That said, Padre Font displayed a canny eye for natural history in his entry for December 9, 1775:

"…On the road about a league after starting there is a salty lagoon without pasturage, and at about four leagues a little well of salty water which Father Garcés called El Rosario... On account of the unfruitfulness of these lands, so level, and of the aspect of the sand dunes, and especially of the abundance of shells of mussels and sea snails which I saw today in piles in some places, and which are so old and ancient that they easily crumble on pressing them with the fingers, I have come to surmise that in the olden time the sea spread over all this land, and that in some of the great recessions which the histories tell us about it left these salty and sandy wastes uncovered... It is not possible that people should have made such mountains of shells by carrying them from the sea so great a distance merely to bury them in piles. All of which, although merely conjecture, has a high degree of probability."

At this point the expedition had just left Laguna de Santo Olella, Site #44 on this map. It's southwest of Yuma in Baja California, west of the Colorado River, and well north of the Gulf of California. We know today that he was completely correct: the Gulf had been this far north, and even farther, thanks to tectonic shenanigans, and had left beds with marine shells. Excellent reasoning by the Padre, without a geologic or paleontologic framework to lean on. One slight catch for the National Historic Trail, though: as noted, this site is in Baja California. Did he observe any fossils in what is now the United States? On December 11, on the part of the trail that crosses the international border, he reported

"One sees along the way many piles of mussels and an infinity of sea snails, very small and spiral shaped, and in places as white as flour. This confirms my opinion that this is a sea beach, and although the sea has reached here sometime, yet no barrancas are found like yesterday."

We're closer, although technically it's possible he saw them entirely on what is now the Mexican side. A few days pass without more shells, then bingo. On December 19:

"...We set out from San Sebastián [Site 49] at one o'clock in the afternoon, and at half past four halted at a flat [Site 50] with some galleta grass but without water, having traveled some four leagues west by north. The road is level, with sandy but firm soil, having some mussel shells and sea snails..."

At this point we are well within California, actually just east of Anza-Borrego Desert State Park in the Ocotillo Wells area. Not only does Font get credit for an astute inference about natural history, but he also cinches Juan Bautista de Anza National Historic Trail as a fossiliferous NPS unit (and one of the few with a report predating the Declaration of Independence).

World of Stone II: The Hinckley Sandstone

While on a brief trip up north recently (Moose Lake Agate Days, naturally enough!), I spent an afternoon around Sandstone and Banning State Park. The name of the town is a good clue as to what I saw there.

Why, yes, sandstone!