Stop 10.  Point Ann

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As drove from the main park area and north we  descended along the vegetation-covered valley wall, passing only a few small exposures of Oneota Dolomite until we entered the town of McGregor.  There is probably little, if any, Shakopee Formation along this route due to the localized deep truncation of the Prairie du Chien Group by the pre-St. Peter unconformity.   At the south end of town several old lower Oneota quarries, now occupied by various buildings, are visible.  Below the Oneota, at the north end of McGregor, the Upper Cambrian Jordan Sandstone is well exposed.  Stops 10-13 will be in town to look at the upper part of the Jordan.

Hike to Exposure of Jordan Sandstone on Point Ann Near Grain Terminal

 

Overview of the Cambrian Jordan Sandstone
in Pikes Peak State Park

by Robert McKay, Senior Research Geologist
Geological Survey Bureau, Iowa,  Department of Natural Resources

 

 

Topographic map of the McGregor area showing the Parking Area (P) and Field Trip stops 10 through 13

 

The area around Stop 10 is a very busy grain handling facility.  The road is narrow and there is little room to stand in the ditch, so be aware of the automobile and truck traffic.  Also, if you go near the railroad grade, be alert for train traffic.

 

 

 Jordan Sandstone at  Stop 10, Point Ann

 

The last stops of the day will focus on looking at the upper half of the Jordan Formation in the downtown area of McGregor.  The outcrops in town are well exposed and are unique in that they are the southern most exposures of the Jordan in Iowa before the formation dips into the subsurface.  The first stop will be at the north end of Point Ann, a promontory above the grain terminal.  There are actually two sections along this bluff, Point Ann South and Point Ann North (see graphic section below).    Click here for a history of the investigation of the Jordan Sandstone and a discussion of the Point Ann sections.

  

GRAPHIC SECTION OF THE STRATA EXPOSED AT THE
PIKES PEAK QUARRY AREA

Click Here for Written Description of
Point Anne North Section

Point Ann South Section

A measured section for the Pikes Peak North Exposure.
 (click on section for a higher resolution image)

 

 

 

Stop 11 is Jordan exposure on the north
side of McGregor on Avenue "A"
about 1 block east of old highway 18

Please be aware of the traffic as you hike through town.
Give the cars and the local residents the right-of-way. 

 

   Hike to Stop 11

 

    Click Here For Stop 11