Plant of the Week

Spiderwort
Tradescantia ohiensis Raf.
other common names: blue jackets, cow slobbers, Job’s tears, Ohio spiderwort, widow tears
Tradescantia: in honor of John (the older) Tradescant, gardener to Charles I, King of England in the early 17th century
Ohiensis: meaning “of or from Ohio”
Spiderwort family: Commelinaceae

Photograph by Thomas Rosburg, Wildflowers of the Tallgrass Prairie: The Upper Midwest, Second Edition

An Interview with Paul Garvin: Part 3

What other areas of geology particularly interest you?
I have a lot of interest in natural disasters, like earthquakes, volcanic eruptions, landslides, hurricanes, and floods, and their impacts on human activity. Decision makers continue to make foolish, and very serious, mistakes about land use because they are ignorant of, or they ignore, simple principles of earth dynamics. I taught several courses at Cornell College on this subject. I am also interested in forensic geology (the study of geologic materials for the purpose of solving crimes).

You are currently doing archaeological research. Tell us more.
My research might best be called mineralogy in service of archaeology. I have a passion for archaeology, which stems from my boyhood days as an amateur arrowhead collector in Idaho. I have no formal training in the discipline, but my knowledge of mineralogy has helped me answer some important questions about how, for example, aboriginal Iowans made their pottery. I have been collaborating with the Office of the State Archaeologist in Iowa City on a study of pottery that was excavated at a site at the Dows Preserve (across from Palisades-Kepler State Park). The Woodland peoples admixed crushed rock (temper) with the clay, in order to control shrinkage during drying and firing, so as to prevent cracking. Through a microscopic study of pottery sherds, I have discovered that different potters preferentially selected (and deselected) specific rock types for inclusion in their pottery. This knowledge has enabled to us determine whether the pottery was made locally or imported to the use area. (There is more to this, but I’ll stop here.)

Paul Garvin, Iowa’s Minerals: Their Occurrence, Origins, Industries, and Lore

Plant of the Week

Purple meadow rue
Thalictrum dasycarpum Fish. & Lall.
other common names: maid-of-the-mist, meadow rue
Thalictrum: the name of a plant mentioned by Dioscorides, an ancient Greek naturalist, and later applied to this genus
Dasycarpum: from Latin, meaning “hairy-carpelled.” (A carpel is the seed-bearing organ of the plant or a unit of that organ.)
Buttercup family: Ranunculaceae

Photograph by Thomas Rosburg, Wildflowers of the Tallgrass Prairie: The Upper Midwest, Second Edition

An Interview with Paul Garvin: Part 2

Is there anything unusual about Iowa’s landforms that would lead to an unusual deposit of minerals?
In general, the answer is no. However, on occasion water-deposited minerals may make the enclosing rock harder and more resistant than normal to the erosional forces of nature. Thus, a localized rock promontory on an otherwise flat landscape might signal the presence of an unusual mineral deposit. Such is the case along US Highway 76, south of Waukon, Iowa, where sandstone has been cemented along a series of parallel fractures by a hard iron oxide. The result is a hard rock mass that rises above an otherwise low-relief landscape.

What are the most common Iowa minerals? The most uncommon?
The minerals which occur most abundantly in the bedrock at the surface in Iowa are calcite and dolomite. These two carbonate minerals are the stuff of which limestone, which is quarried all over the state, is made. The most common mineral in the surficial deposits (stream and glacial sediments and soils) is quartz.

Your chapter about Iowa’s mining industries was fascinating. Many people would be surprised to know that, at its peak, coal mining was second only to agriculture in the state. Given the fact that demand for coal remains high, do you foresee a resurgence in the industry in Iowa?
Without question, there is still a lot of unmined coal in Iowa. (I found that out through some studies I did on Iowa coal reserves for the United States Bureau of Mines back in the mid 1970s.) The problem with Iowa coal is that the coal layers are thin (a few feet thick, at most). In addition, the coal is very high in pollution-causing sulfur,  and removing it is expensive. At present, Iowa coal cannot compete with the enormous deposits of cheap, low-sulfur coal that are being mined in Wyoming and Montana. When they run out, who knows?

Paul Garvin, Iowa’s Minerals: Their Occurrence, Origins, Industries, and Lore

This Week in Iowa Nature

Purple martin scouts arrive to prospect for nesting sites.

The Iowa Nature Calendar, by Jean Prior and James Sandrock

Come see the University of Iowa Press exhibit tomorrow at the 28th annual Prairie Preview!

Location: Parkview Evangelical Free Church

Address: 15 Foster Road, Iowa City

Time: Exhibit opens at 6:30 PM

Click here for more information.

Plant of the Week

Meadow sweet
Spiraea alba DuRoi.
other common names: narrow-leaved meadow sweet
Spiraea: the ancient Greek name; from spiraea, meaning generally “a wreath spiraled or twisted,” for the twisted seedpods of some species
Alba: from Latin, meaning “white”
Rose family: Rosaceae

Photograph by Thomas Rosburg, Wildflowers of the Tallgrass Prairie: The Upper Midwest, Second Edition

An Interview with Paul Garvin: Part 1

Tell us how you developed such a strong interest in Iowa’s minerals that you wrote a book about them.
My interest in geology has always centered on minerals. As a boy growing up in Idaho, I hiked mountain trails, walked the shores of crystal-clear lakes, and pored through the ruins of abandoned lead and silver mines. I picked up and hauled home anything that looked interesting. During my high school years I built a shed, complete with a workbench, storage shelves, and electricity, so that I could house and study my minerals. When I arrived at Cornell College in 1969, I began to look for places to collect and study minerals. I soon became aware of favorite mineral-collecting quarries, mines, and other localities, and I developed research projects for Cornell geology students and myself. Eventually I became aware that I knew more about the geology of Iowa minerals than perhaps anybody else. Jean Prior believed this to be true, and she urged me to write the book.

In simple terms, what’s the difference between a rock and a mineral?
In simple terms, a rock is an aggregate of one or more minerals. Granite is an aggregate of crystals of quartz, feldspar, and minor minerals like mica. Limestone is an aggregate of crystals of the mineral calcite. One can physically break a rock into its component minerals, but one cannot physically break up a mineral into anything but smaller pieces of the mineral itself.

Paul Garvin, Iowa’s Minerals: Their Occurrence, Origins, Industries, and Lore