Summary: Independent Study IGISST Eastern Iowa Geology

Our final project for the Independent Content-based learning of Eastern Iowa Geology included the following:

• Visited numerous local sites with noted earth science teacher, Bill Desmarais.
• Photographed sites.
  
• Took rough field notes in notebooks.
• Converted and expanded notes to create a blog. We are using 21st Century Technology skills to share our findings. (http://igisstsummer2009.blogspot.com/)
• Constructed a summary of our learning in a Tri-fold board, a draft of which was first presented at the July 3, 2009, final meeting of the summer course. We claim: "The Cedar Rapids area provides abundant evidence of glacial activity that dates forward from the Pre-Illinois glaciers." Delivered final Tri-Fold to C. Soldat in mid-August.
  
• Developed a list of lesson options for consideration in our teaching. These include: field trips; speakers such as Bill Desmarais and staff of Bluestone, a local rockshop; review of our iGISST blog; Teacher Domain website lessons, and the CRCSD earth science curriculum.

Entries appear in reverse chronological order. To successfully read the blog one can click on the menu on the right side or start at the bottom and read forward. To clarify the dates shown, on June 13, we entered a template of a post for the various locations we planned to or already had visited. The actual entries were completed at a later time.

We hope you enjoy reading our content-based experiences and observations.

Terri S. Schott 558-1007
Marion J. Patterson 558-4257

Stone City and Maquoketa Caves

Stone City is a small community located about thirty minutes northeast of Cedar Rapids. The remnants of quarrying glory and Artists' inspirations provoke strong nostalgia even today. Practical people live nearby and frequent the Stone City General Store, a patron-friendly establishment with deep connections to the quarry industry. The Weber Stone Company provides year-round employment and a glimpse into Iowa's geologic history.

Directions: Getting to Stone City - North on Iowa Hwy 13 to County Home Road (E34). which becomes Friendship Road in Viola. East about nine miles to Co Rd. X 28. North three miles to Stone City. Mt. Hope quarry is to the west about a half mile at the bottom of the road at the Wapsipinicon River. The active quarry is to the east through the village and on the north. An excellent stop for refreshment is the General Store.
From the Weber Stone Company website:

Geological Information

Anamosa Limestone, a Dolomitic limestone, is a prominently laminated magnesium limestone that was deposited regionally approximately 420 million years ago across the Midwest in the Silurian interval of geological time. Numerous independent lines of evidence confirm that, at that time, Iowa lay in the tropics south of the equator. This distinctive stone forms part of the Gower Formation, the youngest Silurian strata in Iowa. It represents the accumulation of lime extracted from seawater by animals and plants for support of their soft body tissues. Soon after deposition, the calcareous limestone was altered by infiltration of magnesium from the seawater to form dolomite. Crinkly laminations reflect the geometry of thin algal mats on the sea bottom, and planar laminations likely formed in response to seasonal or periodic changes in water chemistry. Alternations of lime mud and sand document the history of calm water interrupted by periodic storms. The rarity of most fossil groups reflects the biologically hostile marine environment. Identical laminated dolomite strata are found associated with thick rock salt deposits in the Silurian of Michigan, and scattered evidence of the former presence of gypsum salts is also noted at Stone City. In shallower water areas adjacent to the sites of Anamosa Limestone deposition, corals, brachiopods and other marine invertebrates built spectacular contemporaneous reefal mounds that are now prime sources of concrete aggregate at other Iowa quarries. Storm erosion of these mounds provided the source of interbedded lime sands locally seen within Anamosa beds, although very few fossils are present in the Anamosa Limestone quarried at Stone City."

Coralville Spillway and the Devonian Gorge

The Floods of 1993 and 2008 reveal the immense power of water. These floods carried a fraction of this power compared to the water that shaped our world in glacial times. The layers and weight of ice, the outflow of glacial meltwater, and the erosive rains that interspersed the time periods must have been incredible. Today's evidence includes the river valleys with their "underfit" streams, bluffs along rivers, bedrock with glacial grooves running east and west, fossils embedded in the limestone layers below the spillway at Coralville, and the highly eroded bank further down the Devonian Gorge.

The theory of the jostling of the plates as South America shoved into North America is evident with the bending of the rock layers. A prominent fracture running NE to SW across the Gorge demonstrates how water flows and the karst development of the dolomite.

Questions: Looking at the pools teeming with life, can this be an example of how mudstone formed and the fine layerings of sediments? (Provided that no other flooding or water release were to happen, which is unlikely.) Where did the peat come from? How thick was the loess soil that rested on top of the rock and peat?

Directions: From I-80 take exit 244, take Dubuque Street north 3 miles to West Overlook Road turn east and proceed 1/4 mile to the park entrance. Follow the signs once in the park to the desired area.

Palisades-Kepler State Park

Palisades-Kepler State Park located a few miles southeast of Cedar Rapids is an area rich with crinoids in the Palisades-Kepler Mound Facies. Experts describe this area as "...a series of coalesced mounded features termed a mound complex." Essentially multitudes of brachiopod molds, crinoid wackestone and packstone fabrics, rugose corals, gastropods, nautiloids, and trilobites are present. What this means for amateurs explorers is an opportunity to observe ancient formations and begin to grasp the significance of our earth's history. (see Palisades-Kepler guidebook # 68)

During our tours to Palisades-Kepler a major question emerged: Why did the Cedar River cut through the rock here instead of making its way around through softer materials? In at least three places that we know, the Cedar did just that - cut through hard rock. One is just up river at the intersection of Hwys 30 and 13. The Cedar cut through a bank and before it did, much ancient glacial sand was left behind and is evident today along with the newer layers of sand left from modern floods. Another cut through is at the old landfill, formerly known as the quarry on the south east edge of the City, but on the SW side. It is diagonally across from Cargill and the remainder of the ledge is evident there. So, why did the Cedar cut through instead of go around? John Dunkhase posits with a similar case of the Black Canyon of the Gunnison, that, a channel started by cutting through a softer material on top of the hard rock. Then, when the water ground down to the hard rock, the channel was in place and the water continued on this path as the one of least resistance.

Questions: How close did the glacier come in relation to Palisades?
How are paleosols different from "newer" soils? {Is a fossil soil, usually buried; indicates weathering of an earlier, stable land surface. Prior}
What is the relation between the Mt. Vernon Paha and Palisades formation?
An environmental issue rose: Prairie Soils hold water (G Wilhelm) sometimes up to 50%! Today's soils are degraded. What impact does this degradation of the soils have on flooding? In what ways would we have been less vulnerable if the soils were in better condition?

Directions: Travel South on I-380, East on US Hwy 30 about 12 miles. Look for sign on south side of road before Mt. Vernon. Follow park road to the River.

Linn County

How lucky we are to live in Linn County, Iowa! A bedrock map of Iowa reveals that Linn County lies at the junction of distinct landforms and geological history. So amateur geologists have at their disposal a variety of formations to examine in a relatively close area. As per the Iowa Geological Society maps (Iowa Geology # 22, 1997, page 5), two distinct bedrock formations underlie the area: Precambrian and Devonian. We will primarily be investigating Linn and northern Johnson Counties' geological past.

Annotated Diagram of Bever Park

A crude first attempt at digital annotated diagram on Blogger. (I had to take a picture and then put that up rather than put in the original document which is in the larger three ring binder.)

Questions: * Why is the valley so large for such a tiny stream that appears to come from nowhere other than storm drains? It appears rounded so perhaps is glacial but also shows influence of water flowing through.
* Is the ledge along the stream by the animal farm bedrock?
* Where do the drainage pipes come from and why were they inserted?

Directions: Travel on Bever Ave SE in Cedar Rapids. Between Memorial Drive SE and 30th St SE turn into the park on the north side of the road. The large boulder is to the west of the pool. Follow the stream down past the avian display. Another entrance accesses Bever off Grand Ave SE.

KWL

What we know about geology in the area.

• Iowa is impacted by deposition and erosion as evidenced by uplift in the west and continental glaciation.
• Iowa is underlain by Precambrian rock.
  

What We Want to Know: PBL Cedar Rapids area demonstrates evidence of past glacial history.

• What were the geologic forces that shaped Cedar Rapids?
• What are the major geologic time periods and their characteristics?
• How do lay people read the surface of the landscape?
  
• What are some pieces of evidence that we see today that indicate what happened in the past?
• What are some notable local sites we can visit to show students these forces?
• Why is Sioux Quartzite exposed in NW Iowa and SE South Dakota?
  

What We Learned about geology:

• Both repeated uplifts and erosion shaped Iowa's surface. {Uplifts in the west and repeated glaciations.} (Iowa Geological Society and Landforms of Iowa)
• Major geological time periods are readily available in geology books and take time to learn and understand.
• Reading the surface: Aerial maps, becoming familiar with characteristics of landforms such as pahas (nw to se), bogs (fines hold in moisture and remnants of glaciers), cut bank strata (top soil, subsoil, parent material and bedrock)
• Evidence from today and notable sites in Eastern Iowa: glacial erratics (Bever Park), alluvial deposits in the river (especially after the flood), eolian deposits (sand dunes in NE Iowa), Stainbrook Geological Preserve (glacial grooves), pahas (Hwy 13 and Mt. Vernon), and cut banks with exposed layers (Ely).
• Why is Sioux Quartzite exposed: During the Cretaceous Period these sandstones formed and then erosion took off layers that were on top. (pgs 80-82 Landforms of Iowa).