The area between St. Peter and Mankato has many limestone and sandstone quarries, including this one called Jefferson Quarry.  It is on the northeast end of Mankato and is visible on the right side of Highway 14 just after crossing the Minnesota river.  Looking above the limestone blocks between the trees in this photo you can see the other side of the river valley.  The photo below is a closer view of some of the limestone that has been quarried here.

 
This photo is of another quarry site owned by Jefferson Quarry.  It is just north of Mankato on county road 5.  Here it is easy to see the bedding structure of the limestone.   The photo below is a closeup of an unconformity about eight feet below the surface with a line that looks like it could be mudstone or shale.
A few miles further north on county road 5 just before the town of Kasota is a sandstone quarry operated by UNIMN.  The sandstone is about 99% pure quartz of very uniform size, well rounded and very little cementing.  It is processed and used for making glass or computer chips.  The photo at the right is of a pile that has been mined but not processed.  It is almost as white as snow.

The photo below shows the quarry.  The sandstone is just a few inches below the surface and in the quarry looks like a snow bank or beach sand dune on one of the white ocean sand shores.

This photo is at the entrance of a Nicollet County Park on Highway 169, about halfway between Mankato and St. Peter.  The cliffs and hills all around the park are of sandstone.  It is very easily carved with a stick and many people have left their temporary mark in the stone. 

The lower photo shows a closeup of the sandstone.  The bedding here is very visible and at the surface not unlike the bedding of sand in the Holman Esker on our first stop.

Along Highway 169 between St. Peter and Mankato there are a few road cuts into the bedrock.  Stopping to examine one I found that most of the rock is sandstone (below) but found an unusual formation at one point that is quartzite (right and below right).  I was not able to break off a sample to examine more closely but I would expect that the quartzite should be similar to the Sioux Quartzite in that it is a sedimentary rock cemented in some way, not a true quartzite formed by metamorphosis.
The human reaction to the forces of nature are almost amusing at times.  These two photos show one of the attempts at holding back "Mother Nature".  The city of Henderson northeast of St. Peter is in the Minnesota River Valley.  When the river floods, as it does every few years the town would be under water.  The solution is to build a dike with this removable wall across the road.  When it floods the gates are put in this wall to hold back the river.  I think a better solution would be to have more swamps and other water holding areas up stream (it would also help to keep out the large amount of silt in the Minnesota River) or to stop building in the river valley. 
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