AMNICON FALLS STATE PARK – SANDSTONE QUARRY
In order to log this Earthcache as a find, you must complete the following tasks and email the answers to me ON THE SAME DAY AS YOUR FOUND LOG.
1. What two sequences of Sandstone have occurred in the Lake Superior Region?
2. What part of the three in the Sandstone Group identified in No 1. are you seeing at the Quarry?
3. From the information at the Quarry Interprettive Sign: Fill in the blanks -- "At the turn of the century, sandstone, also called ____________, was a popular construction material. This quarry was established in 1887 and during the _____ years of operation produced over a _____________ cubic feet of stone that was shipped to Superior, Chicago, Sioux City, Omaha St., St. Paul, Minneapolis and other Midwestern cities. ________________ in Superior, Wisconsin was built from the sandstone from this pit."
4. At the Quarry Edge waypoint, estimate how wide this strip of land is from the pit to the river. In your opinion and from your observation, why would this strip of land have been left to stand and not quarried?
5. In your own words describe the sandstone in the quarry or at the edge of the river. (color, unique features, etc.)
Welcome to Amnicon Falls State Park, one of my favorite state parks! The park is open from 6 am to 11 pm year-round. There is a vehicle entrance fee of $3-11 per day or $13-38 for an annual pass depending on which state your vehicle is licensed for. This state park has a credit card machine at the entrance for payments. A window receipt will be issued.
BACKGROUND - Amnicon Falls State Park, established in 1961, is located about 7 miles southeast of the city of Superior in Douglas County. It features a series of four waterfalls and rapids along the Amnicon River, a state-designated Outstanding Resource Water. About 12 miles south west of the park, Amnicon Lake provides the origin to this warm water river, which then flows northeast to its outlet in Lake Superior. The waterfalls in the park can be observed from the historic Horton Covered Bridge, trails along the river and from the rocky shore of the river.
Amnicon Falls State Park has long been known as the best place to observe and study the remarkable geologic feature known as the Douglas Fault, a prominent line along which igneous basalt rock upstream was lifted above reddish sandstone downstream; these falls (and others in the region) were created by the Douglas Fault. The Amnicon River splits into three branches along the fault; however, the third branch is quite small and only flows during times of high water (“Now and Then” falls). Signs of a historical sandstone quarry and early days of logging remain evident. Unique red clay wetland soils at the park typify this region of Wisconsin. Source: (1975 Master Plan, WDNR https://dnr.wi.gov/topic/lands/regionalplanning/superiorcoastalplain/documents/AmniconFalls.pdf)
GEOLOGY IN THE PARK: As you enter the park you are witnessing a billion years of geological activity! Evidence of volcanic eruptions, the advance of great oceans, the formation of sandstone, earthquake movements and glaciation can all be seen. You may want to visit the falls first before proceeding to the earthcache site.
The dark basalt seen at the Upper Falls is the solidified remnants of lava that flowed across the entire region about a billion years ago. The Lower Falls flow over Lake Superior sandstone. It was formed from sand deposited by streams flowing into an ocean that covered much of Wisconsin millions of years ago. The sandstone formed in horizontal layers, which you can see on the riverbank. The sandstone also has vertical cracks or joints. When the river undermined the rock wall on the northeast side of the river, large pieces of sandstone separated from the parent mass along the smooth joint planes.
About 500 million years ago, there was a tremendous fracturing and movement of the basalt bedrock. The crack, called the Douglas Fault, extends from east of Ashland, Wisconsin, to near the Minnesota Twin Cities. The bedrock south of the fault slowly moved upward and to the north at a 50- to 60-degree angle. More recently, great glaciers moved across the area.
To learn more about this fascinating story, pick up a free booklet about the geology of Amnicon Falls at the park office. The booklet will guide you to stops along the walking trails at the waterfalls and explain how the tremendous forces of nature have combined to produce this state park's outstanding scenery. Source: https://dnr.wisconsin.gov/topic/parks/amnicon/geology)
GEOLOGY OF THE BAYFIELD GROUP OF SANDSTONES: There are two sandstone sequences in the Lake Superior region. The first is the older sandstones (the Freda) that had been tilted and deformed along with volcanic rocks to form the Lake Superior syncline (a trough or fold of stratified rock in which the strata slope upward from the axis}. If interested in seeing Freda sandstone up-close-and-personal, find this earthcache: https://coord.info/GC2EG5F “What’s Up with the Freda Sandstone” due north of Saxon, Wisconsin on the shoreline of Lake Superior.
The second is the thick sequence of flat-lying sandstone, that overlay the Freda sandstone which is called the Bayfield Group. This group is well developed and highly visible throughout the Bayfield Peninsula (which gives the sandstones their name) and extends southwestward through Superior, Wisconsin and into Minnesota, where they are called the Fond du Lac and Hinkley sandstones.
Outcrop data measurements show the Bayfield Group may be 4,300 feet thick, and more recently data indicates it may reach over 7,000 feet.
The Bayfield Group has three subgroup formations: The Orienta, the Devils Island, and the Chequamegon Sandstones in ascending order. Simply: Think of this as a 3 Step Stairway made out of Sandstone. We begin at step 1: The Orienta Sandstones is a red feldspathic sandstone about 3,000 feet thick; Step 2: the Devils Island Sandstone is a well-sorted, very pure quartz sandstone about 300 feet thick; the uppermost layer, Step 3: the Chequamegon Sandstone, exposed on the Bayfield Peninsula and the Apostle Islands, is again a red feldspathic sandstone with a thickness of perhaps 1,000 feet. Source: Geology of The Lake Superior Region, by Gene L. LeBerge, page 166.
SANDSTONE QUARRY SIGN: At the quarry is an interpretive sign. Several answers for this earthcache will be taken from the sign.
The Geocache Notification Form has been submitted to the WDNR Manager, Kevin Fiend, of the Amnicon Falls State Park for this specific cache. This DNR Notification form and land manager information form was submitted: http://dnr.wi.gov/files/PDF/forms/2500/2500-118.pdf