Arcola Bluffs Day Use Area

It's been a good while since our last St. Croix post, hasn't it? I wanted to let you in on a fun place I recently visited for the first time; Arcola Bluffs Day Use Area. This site is not widely known; there's this article (with much more artistic photos than my own), an NPS cultural landscape assessment from 2018 that weighs in at 204 mb (NPS 2018; absolutely worth it if you want a thorough understanding of the site, and also includes a section on Fairy Falls), and then some short pieces here and there, and that's about it. Visiting it, though, you'll discover great geology, views of the river and the historic Soo Line High Bridge, forest and prairie settings, and some evocative ruins.

Arcola Bluffs Day Use Area is not huge, just a little more than 200 acres, with a "suggested" trail network less than 4 miles (6.5 km) long if you hike all of them. There is a certain amount of up and down involved, but the terrain is not rolling; rather, you can go down as far as the river level and then back up to return. Going back up can be a bit of a hike, but it doesn't feel as strenuous as, say, walking back from the falls at Willow River State Park or from the St. Croix at Kinnickinnic State Park (possibly because those are paved trails and the Arcola trails are gravel at most). Parking is limited, basically a pull-off on the side of Arcola Trail; if they aren't all giant pickups, there's space for about ten cars here. The map posted at the entrance is accurate for the main trails. There are also, of course, numerous social trails. If you choose to go "off-road", though, do keep in mind that natural areas in the St. Croix Valley are abundantly supplied with ticks. (By which I mean step in the wrong place and it's "Why, a minute ago there was nothing on me, but now there are three of them on my leg.")

Park entrance map; the two there-and-back trails on the right follow successively lower bluff tops.

This map, from the cultural landscape analysis (NPS 2018), gives an idea of the topography plus locations of some of the major features.

The layout of Arcola Bluffs is a double bluff separated by a flat to gently sloping area, with some old drainage to jumble things (especially in the north). The upper bluff is not quite as steep as the lower bluff, and it looks like the Jordan Sandstone is exposed toward the top. (There's some stuff at the *very* top that reminds me of sandy Prairie du Chien, and the Prairie du Chien is definitely present nearby because there used to be a quarry north of the railroad, but topographic breaks tend to form at contacts.) The upper bluff trail has its charms, but the view into the river valley is not quite as good as you get from the lower bluff due to the vegetation. There *is* at least one place other than the suggested trails where you can go down quite easily and conveniently from the upper bluff (it was *so* convenient it seemed like it must have formerly been in use when there were farms below), but once below the bluff the apparent trail petered out. (This would actually be a natural route to join to the lower bluff trail to form a loop, rather than having two there-and-back tendrils.)

Looking up at some Jordan Sandstone in a little nick in the upper bluff.

The flat between the upper and lower bluffs formerly saw use for a railroad and farming. You can find several stone foundations around a meadow area, and part of the trail system is developed where the Wisconsin Central Railroad used to go on its way to the river. The abutment and piers still remain in the south part of the day use area, where there is also a small waterfall. (Some enterprising folks have clearly gone down to the river level from the abutment, but I don't recommend it. If you want to see that area, you're better off using a boat, or waiting for the river to freeze over in the winter.) If you continue on the lower bluff trail to its south end, you will find a beautiful view south down the St. Croix.

This neat old tree growing in the ruins of a barn makes a wonderful landmark in the meadow area, although standing out in the field like it does I wouldn't be surprised if it winds up struck by lighting (several charred stumps can be seen around the bluffs).

This little building near the lip of the lower bluff would have had a marvelous view of the river.

The piers for the old railroad bridge.

That view I mentioned.

Going back north on this trail, you have a couple of choices for going down to the river level. First, there's "the Cut" down to the river, which is a road cut through the bluff for unknown reasons sometime between 1957 and 1964. I didn't have the time to check it out thoroughly, but it looks like a great place to examine some stratigraphy.

Maybe planned as a boat launch? At any rate, plenty of rocks to look at.

You can also follow the old rail trace north to another descending trail nearer to the most famous sight of the day use area, the Soo Line High Bridge. In this area you will find more traces of former use, in this case remnants of a summer property built in 1911 (the Heath property). Social trails connect "the Cut" to the old Heath property below the bluffs. (You may also observe trails going up to the High Bridge, but *ahem* you are not supposed to be there. The bridge is in use for rail traffic and is not part of the Arcola property. Just so you know...) A couple of sinuous ravines can be seen snaking their way west and north.

And there it is...

The lower bluff is also sandstone and resembles the rock seen downstream at the St. Croix Boom Site, which is our old friend the Mazomanie Formation. There's something else here, too: down near the base you can sometimes see a greener, more fine-grained rock, with seeps forming at about the contact. I'm interpreting this as the Reno Member of the Lone Rock Formation, as it doesn't remind me of the Tomah as I've seen it up at Marine on St. Croix. Schwartz (1936) presented a geological section from the Soo High Bridge that was reprinted with stratigraphic modifications by Stauffer and Thiel (1941), but it should really be revisited because of the redefinition of the Franconia and the creation of "the Cut". I'm going to need to investigate this area some more!

This looks rather like a contact or intraformational break in the sandstone.

This is pretty clearly not standard Mazomanie-type sandstone.

Water coming out at the seeps likes to make these mini step-waterfalls.

One more for the road: the view of the High Bridge from the area where "the Cut" ends.

References

National Park Service (NPS). 2018. Arcola Bluffs and Fairy Falls, St. Croix National Scenic Riverway: Cultural Landscape Analysis. National Park Service. [note: 204 mb file]

Schwartz, G. M. 1936. The geology of the Minneapolis–St. Paul metropolitan area. Minnesota Geological Survey, St. Paul, Minnesota. Bulletin 27.

Stauffer, C. R., and G. A. Thiel. 1941. The Paleozoic and related rocks of southeastern Minnesota. Minnesota Geological Survey, St. Paul, Minnesota. Bulletin 29.