Sluice Boxes Geology Field Trip and Hike

September 5, 2005

This is a hike through the lower half of the Sluice Boxes State Park in Central Montana looking at the geology and other natural features.  Good scenery, interesting geology.  In the photo on the left there is a tree growing out of the top of a pillar of limestone.  The pillar is on the edge of a 100 foot vertical cliff, similar to the cliff on the other side of Belt Creek.

• Location -- The Sluice Boxes State Park is located about 40 miles southeast of Great Falls, Montana in the Little Belt Mountains.  Take U.S. Highway 87/89 for about 25 miles (from Great Falls) to the Armington Junction, where a large Rest Stop is located.  Turn right on U.S. 89 towards Monarch and go about 10 miles to the well-marked turnoff for the State Park.  It is the Evans-Riceville Road approximately a quarter of a mile past Mile Marker 62.  Go to the meeting place--the parking area for the State Park next to Belt Creek.



• The Railroad -- The Great Northern Railroad was built from Armington Junction through the Sluice Boxes to Monarch in 1890.  It reached the lead/zinc/silver mines in both Barker and Neihart in the following year at the height of the "Silver Boom."  The "bust" occurred 2 years later with the Silver Panic of 1893.  The "Fish Train" service was very popular with Great Falls residents.  Fisherman were dropped off at various points along Belt Creek as the train made the morning trip to Neihart and then they would be "picked up" on the late afternoon trip back to Great Falls.
  
  Limestone was quarried at Albright where it was roasted in lime kilns (see photo on left).  Coal was brought to Albright by train from the coal mines at Belt.  Heat in the kilns drove off the carbon dioxide CO₂ in the limestone Ca(CO₃) to make quick lime CaO.  Adding water to quick lime created slacked lime Ca(OH)₂.  The slacked lime was used to make mortar and also plaster for finishing interior walls in both residences and commercial buildings.
  
  Floods periodically damaged bridges across Belt Creek, particularly, in the Sluice Boxes, contributing to high maintenance costs.  The railroad continued to operate, however, until the end of World War II.  The tracks were removed in 1946.  A modern highway to Monarch, Neihart, and White Sulphur Springs was completed in 1954.



• How To Carve A Sluice Box -- The feature that makes this State Park unique in Montana is the inner gorge with vertical walls.  What is the process that can carve a "sluice box" out of solid limestone?  The answer can be seen in the top photo.  The boulders in the creek bed are strong, resistant rocks, such as porphyry and diorite.  During highwater and floods Belt Creek becomes a high-speed stream of liquid with abrasive particles.  A diamond saw can cut through rock because of the hard diamond abrasive particles in the rim of the saw.  Similarly in the case of Belt Creek it is the hard boulders that act as an abrasive and cut the vertical "slot" in the limestone.  During highwater or floodtime, such as shown on the right, one can hear the boulders hitting one another as they move down Belt Creek.  Although a lot of limestone rocks fall into Belt Creek, limestone does not last very long when pounded with very tough rocks, such as porphyry and diorite.
  
  Sluice boxes were used by early miners to recover gold.  The heavy gold nuggets collected behind the riffles in the bottom of the box.  Although the Neihart Mining District and the Barker/Hughesville Mining District are upstream, these are lead/zinc/silver deposits, not gold deposits.  The gold deposits in Montana are in the Little Rocky, Moccasin, and Judith Mountains and in the Helena area, not in the Little Belt Mountains.



• Karst and Caves in Sluice Boxes State Park -- The sluice boxes are carved in Mississippian-age Madison Limestone.  Limestone is slowly soluble in water and many caves can be seen as one hikes through the gorge.  Even more impressive than the caves that appear as open holes in the cliffs are collapsed former caves.  Some of these were sizeable.
  
  As Belt Creek flows through the Sluice Boxes, it loses water.  Water goes into the Madison Limestone Aquifer.  Most of the water that flows underground comes out at Giant Springs.  However, some of the water flows underground all the way to Manitoba.



• The Hike -- The hike follows Belt Creek from the bridge near the mouth of Logging Creek to the Parking Area at Riceville at the north end of Sluice Boxes State Park.  The distance is approximately 7 miles. Most of the hike is along a well-defined trail.  Part of the hike is on a former railroad bed.  The hike goes through one tunnel, across a short trestle, and crosses Belt Creek about 14 times.  This is a hike for August or September when the water is relatively warm.



• Field Trip Leaders -- Sheila Rice will lead the hike. Dr. David Baker, Earth Scientist in Monarch, will comment on the geology and other natural features.



• Registration and Cost -- There is no charge for the field trip; however, prior registration is required. The group size is limited. To register fill out our on-line registration form. Meeting time is 8:30 a.m.

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