The Lower Carver Rapids on the Minnesota River

Historically, the upper and lower Carver Rapids on the Minnesota River stopped steamboat traffic up the Minnesota River during times of low water.  Having the water level on the river low enough to expose the rapids had been described as a rarity, though the rapids have been exposed for much of the past year due to dry conditions found throughout the Minnesota River basin.  My first trip to the rapids took place last fall when the river was at 5.37 feet, according to the closest river gauge, and can be re-visited here.  Because of the lack of snow last winter and continued dry or drought conditions this summer, the river level has continued to fall to a current level of 3.66 feet.

The picture below shows the lower rapids a year ago from the southern bank of the Minnesota River.  Though the upper rapids were exposed at the time, the lower rapids were seemingly just below the surface of the water.

Ten months later, with the continued drop of the Minnesota River, the lower rapids have been exposed.  The picture below was taken from the northern bank of the Minnesota River.

The rapids are created as water flows over the Cambrian-aged Jordan Sandstone.  The bedrock here is one of the very few locations of exposed bedrock in Carver County, Minnesota.

Below is a 1.15 gigapixel image of the lower Carver Rapids taken from the northern bank of the Minnesota River.
To see the full size gigapan, click here.

Minnehaha Falls - In a dry year

Minnehaha Falls is a 53-foot waterfall found near the confluence of Minnehaha Creek and the Mississippi River.  The falls form as the creek flows over the Platteville Limestone caprock to erode the underlying and weaker St. Peter Sandstone.  Between the limestone and sandstone is a thin layer of the Glenwood Shale.  The Platteville, Glenwood and St. Peter are all Paleozoic in age.  An earlier write-up of the geology of the area can be found here.

The month of September 2012 was the second driest month of September on record for the Minneapolis-St. Paul area.  Officially, just 0.30" of rain fell (the driest month of September was in 1882, when 0.27" of rain fell).  Ironically, September 2011 was the third-driest month of September with 0.36" of rain.

The lack of rain has had an effect on Minnehaha Falls, it is nearly dry now.  The source of Minnehaha Creek is Gray's Bay on Lake Minnetonka and in periods of low rain, the outlet to the creek is closed to preserve the lake level.

Without the flowing water, it is much easier to see the sandstone, shale and limestone layers.

See the full size version of the gigapan here.

The Kensington Runestone

Eight Gotalanders and 22 Norwegians on (this) reclaiming/acquisition journey far to the west from Vinland.  We had a camp by two (shelters?) one day's journey north from this stone.  We were fishing one day.  After we came home we found 10 men red with blood and death.  Ave Maria.  Save from evil.  There are 10 men by sea to look after our ships fourteen days journey from this island.  Year 1362.

Incription on the Kensington Runestone.

In September of 1898, the Kensington Runestone was found near the village of Kensington by Swedish immigrant Olof Ohman and his two sons Olof, Jr., and Edward.  The group had been clearing trees on the end of the family plot when they found the runestone.  After cutting the roots of a 25-35 year old aspen, they found a several hundred pound, rectangular stone wrapped within the roots.  It was Edward who noticed the inscription on the stone first.

The Olof family farm where the runestone was discovered is now a county park call Runestone Park.  The location were the runestone was found is marked by a small plaque, just downhill from the United States, Minnesota, Swedish and Norwegian flags.  The Runestone is now displayed at the Runestone Museum in Alexandria, Minnesota.

The Runestone is a rectangular stone that has been obviously split to be that shape.  It is a grey, meta-graywacke glacial erratic.  This rock type is commonly found in the Animikie Basin of East-Central Minnesota and is Paleoproterozoic in age (1,800 to 2,100 million years).

At the time of the discovery, many scholars immediately announced that the runestone was a hoax.  But in 1909, after examining and studying the runestone, Minnesota state geologist, Newton H. Winchell said that "I am convinced that the stone is not a modern forgery....".

Mineral weathering rates provide some evidence that can be examined on the runestone.  Shortly after the discovery, Olof Ohman used a nail to scratch out some of the inscription.  Some of the runes were not scratched out.  The runes that were not scratched out show extensive weathering, pyrite crystals have completely weathered away leaving iron oxide-coated pits.  In comparison to other stones, the weathering of this mineral would have taken more than 23 years, twenty-three years before the stones discovery, Olof Ohman was still living in Sweden.

Comparing the weathering rate of biotite mica in the runestone to the rate found in slate tombstones in a similar evironment, the inscription has been weathering for longer than two hundred years.  The mica minerals in 200-year-old tombstones have begun to fall away, on the runestone, all the mica minerals on the man-made surfaces have weathered away.

There are two options when considering the runestone:
1.  The stone is a hoax.
2.  The stone is real (implying that Europeans reached the interior of the North American continent earlier than commonly thought.

Two books can be read for differing ideas about the history of the runestone, if it is real.
1.  The Kensington Runestone, It's Place in History -  this book describes how the stone could have been carved one day's walk from Mille Lacs Lake in Central Minnesota and how the Dakota Tribe was given/then carried the stone to it's eventually buried location.
2.  The Kensington Runestone - Compelling New Evidence -  this book really lays out the evidence for the stone's authenticity, including the geologic evidence and the linguistic evidence (including ancient Swedish runes that were discovered in the 1900s but are also inscribed on the runestone).