Don Robinson on the Rocks

Hiked this morning at Don Robinson State Park, with all its raw-looking, yellow-orange must-be-iron-in-there sandstone rock cuts. I'd taken some wildflower photos and then propped myself up to rest against a rock cut that exposed alternating layers of sandstone and limestone, like cake, and saw some of the yellow rocks freckled with black.

Closer inspection showed the freckles to be what looked like tiny plant fossils. (Photographed with a magnifying lens; actual size, 3cm.) Amazed and excited, I looked harder. Most of these enchanting fernlike things were pressed into a single layer of the rock. Five miles away at my place we don't have this type of sandstone and we don't have these.

The dark lines like black pepper are the "fossil" layers.

But, surprise--they are not plants! They are dendrites, deposits of manganese oxide, that have fooled a whole bunch of people, including me now, into thinking they are plant fossils. Internet says, "They form as water rich in manganese and iron flows along tiny cracks between layers of limestone and other rock types." I don't know about the manganese, but the rock there has iron and limestone, so if this is Wednesday it must be dendrites.

Valley View Glades Natural Area

On Highway B near Morse Mill, in Jefferson County, is a conservation area called Valley View Glades. I hiked its trail late last year and vowed to return when spring came, because a glade in bloom is a marvelous thing to see.

Come on out soon. You needn't walk the 2.6 mile trail loop. The most amazing vistas in Valley View Glades are at the beginning of the trail, whether you choose to walk left or right. There really is a valley view. Here's more info and a map.

What's a glade? It's not that stuff in cans: It's an outcropping of rock and thin soil, just enough to support echinaceas, coreopsis and other wildflowers, on a south-facing hillside--a unique kind of ecosystem. Missouri's natural glades get clogged up by invasive red cedars, so conservationists cut down the cedars to preserve the glades' sunny openness and protect the habitat of special creatures such as salamanders who live in glades.

Should you want to hike the complete trail, it's very rocky most of its 2.6 miles. Bring water. I found my walking poles to be most helpful. You will stepping-stone across at least two pretty brooks.

Rare Pink Dolomite

Found this specimen while hiking the rocky 2.6 mile trail at Valley View Natural Area, in Jefferson County, 2 miles south of Morse Mill. It's one of the two areas in Jefferson County where dolomite glades, or rocky outcroppings, often south-facing and hot and dry, are preserved with controlled burns and cedar-tree removal -- the only way to preserve this once-common and precious Missouri natural feature. Glades support wildflowers and wildlife that thrive nowhere else (and are prettiest in spring). Cedar trees are invasives which entered the area along with mass settlement about 150 years ago, and they overtake glades and native oak-hickory forests unless they are stopped.

But we were speaking of dolomite. Even geologists don't agree on what it is, except that it's calcium and magnesium somehow mixed, and rarely there are pink examples of it, probably from being mixed with a little iron. A dryer-sized chunk of petrified mud had this chip broken off of it, revealing lovely sparkling stone bubbles (saddles) and glittering crystals.

I learned today that flipping flat rocks looking for creatures or fossils underneath them -- and not replacing them-- destroys the flora and fauna that lived in that environment. I was never in the habit of flipping rocks but now I know for certain that it's bad manners.