Sunday, June 28, 2020

Revisiting Coldwater Spring and Fort Snelling State Park

The same day I got out to Shadow Falls Park, I also stopped at Coldwater Spring and Fort Snelling State Park. These locations are geologically restricted to the Platteville down to the St. Peter, and the exposures are much more in the bluff mode of expression.

Lo, the type section of the St. Peter Sandstone, mostly behind a wall (probably for the best, given the way people use any handy outcrop of the St. Peter to practice their rock-carving skills)

What impressed me at these sites were the numerous rockfalls. It seemed like a lot, but I don't have the numbers to judge. It would actually be a simple project: somebody could periodically go along the paved path and document new falls by photos and GPS. The rub is that it's also a long-term project; you wouldn't get useful information from a couple of years.

At this fall, out of the Mifflin Member of the Platteville, it's easy to see the lighter color where the rocks used to be.

The outcrops of the Hidden Falls and Magnolia members just north of Coldwater have been taking a beating lately, although I'll grant that it's not as impressive when they only fall a few feet. There's both day-to-day attrition and larger collapses.

If you should happen to go below the paved path, down toward the river (say if you're going into the dog park), you can also see evidence of older disruption, where large blocks of Platteville have been displaced.

If the beds are noticeably tilted, that's a good indication they aren't where they started. (And also the whole "lying in jumbled heaps" thing, that's a good clue.)

A small, gentle waterfall southeast of Coldwater, unnamed as far as I know, running through a cleft in the St. Peter.

Given the geology, fossils weren't terribly diverse or well-preserved. There were the usual brachiopod beds exposed on some of the fallen blocks:

There were also these things. 99.999% says they're a couple of weathered burrows, although the coincidental weathering on the longer of the two made me think of segmented stems when I first saw them, which would be rather odd for the Platteville. Further study of the photo showed that the "segmented" feature was longer than I thought, and that the apparent segmentation was limited to the two lines.

Same photo, light red lines added to trace the features.

Sunday, June 21, 2020

Your Friends The Titanosaurs, part 25: Quaesitosaurus, Quetecsaurus, and Rapetosaurus

Here we are, June 2020, and this is not only the 300th post at Equatorial Minnesota, but also the second anniversary of "Your Friends The Titanosaurs". It seems fitting enough that the two should coincide. This particular set of three titanosaurs covers a pretty broad spread, geographically, from Mongolia to Argentina to Madagascar.

Sunday, June 14, 2020

The gut contents of Borealopelta

Seems like we just had Borealopelta markmitchelli as a major part of a post. Unlike back in March, this time around the famously well-preserved nodosaur doesn't have to share space with any other ankylosaurs. The occasion is the publication of Brown et al. (2020), which describes plant material found inside the carcass of the ankylosaur. This publication is freely available, and if you have any interest in dinosaur paleobiology you ought to snag it (and its supplementary material; never forget the supplements!).

Sunday, June 7, 2020

A note

It's been an intense couple of weeks here in Minnesota, and I didn't feel that my usual thing made much sense. The peonies are just starting to bloom here, so would you accept a kind thought and a flower?

There's a family story with these plants. They're supposed to have been brought to Amery, Wisconsin by family members sometime in the 19th century, then my grandparents brought them to Cottage Grove. When they passed away and their house was being readied to be sold, their children, including my mother, each took some of the plants and planted them at their own homes. Now, that would make for some ancient plants, even for something as famously long-lived as peonies, but I can personally attest to a few of those decades. On the other hand, the flowers themselves are here and gone, blooming for just a short time in early June.