The Oolitic Sand Beach and Shoreline

Turn west from the Egg Island parking lot and go to the Bridger Bay State Beach. Walk out on the beach--most of the sand and surrounding soils are composed of Pleistocene alluvial materials deposited during the rise and fall of ancient Lake Bonneville.  See the geology map from the Utah Geological Survey booklet (listed below) and the graph of ancient lake-level changes or stands.

When you get to the beach wade out into the water and even try floating--feel its buoyancy!  And think about why things float easier in a saline lake. This is also a great place to play in the sand! 
 

Feel the unusual smoothness of the sand with your feet--some say it feels like walking on ball-bearings! What do you think causes this?

Look closer at the sand with a hand lense. Try putting some acid on it with a dropper (like vinegar or lemon juice). What happens?


 You are observing a very special kind of beach--an Oolitic Sand Beach.  This beach is actually composed of sediment that precipitated out of the lake under certain temperature and chemical conditions. The precipitate coalesced around specks of dirt or even minute aquatic organisms producing round ball bearing-like sand grains rather than the more angular and sharp-edged feel of  regular sand which comes from stream erosion.  Regular sand is primarily made of silica, e.g. quartz while Oolitic sand is very high in calcium carbonate.  So, when you put acid on the Oolitic sand it fizzes--regular beach or stream sand doesn't! 
 

Ecosystems on the shorelines of saline lakes show great complexity over very short distances and are much more productive and diverse than you can imagine.  This forms the basis for a food web or trophic chain that supports a great diversity of plant and animal life. Take a walk from the water's edge along the beach inland--that is do a fieldtransect--and you will be able to observe some of this beautifully complex diversity. 

Study the two graphics on this page--they are an excellent introduction to the wetlands and aquatic ecology of the Great Salt Lake! Though you can't see all the salty shores habitats at Bridger Bay you can see several of them. 

Learn more from the Great Salt Lake Project at Westminster College of Salt Lake City. See some of the materials by Ty Harrison a biological ecologist and his students such as the Great Salt Lake Playa Foodweb Project.

Variations in vegetation and animal species in the Great Salt Lake's shoreline habitats correlates closely with percent (%) salinity within the root zone.  This is one of the most critical limiting factors that field ecologists study. This factor helps to explain much of the great diversity of life seen along the edge of the Great Salt Lake--one of the western hemisphere's most productive breeding and feeding areas for millions of birds, as was explained earlier.

Freshwater Ecosystems on the Lake

Some of the habitats not accessible at Bridger Bay include the freshwater marshes or the mixed salt/freshwater marshes and estuaries and other riparian habitats along the Bear River itself and in its delta.

A freshwater marsh near the MBR.

The Bear river is the largest freshwater source entering the Great Salt Lake, but there are other important rivers/deltas as well--see this graphic showing the Bear, Jordan and Weber River Deltas and drainage basins.  The rivers are a fascinating and important  part of the complex ecological system that is found around the Great Salt Lake. Variation in the flow of freshwater into the lake currently and in the past is largely responsible for the lake's changes from being a freshwater body to saline lake.

Habitat and Ecosystem Types around the Lake

Try to visit all the habitat types around the lake as well as those seen here at Bridger Bay and nearby at the MBR. You will observe a great variety that includes: 
 
• the salt lake itself which you've seen here,
• riparian (river) habitats (around the MBR),
• freshwater mud flats and marshes (various places),
• playas/salt flats and salt marshes, 
• sand dunes and beach deposits (Antelope Island),
• sagebrush lands (at locations away from the shorelines in drier lowlands),
• pinon-juniper or oak woodlands (on better drained foothill soils),
• mixed and coniferous forests and alpine meadows (upslope in the mountains and in the canyons).
   
All of these habitats will be seen briefly on this virtual tour or others to come.  You will find that all of them are characterized by predictable biogeographical/spatial-ecological patterns that correlate with many factors: moisture and temperature, soil nutrients and texture, geology and landforms, elevation and drainage, and micro-climate. In addition, even human historical influence has played a part such as introduction of domesticated animals and use of fire.  We will study the human dimension more at the next stop. 

You can read much more on Wetlands and Aquatic Ecology at Robert  Ford's Hydrosphere list.  See also under Limnology--the science of lakes, inland seas and wetlands as well as under the Biosphere. See also Western Hemisphere Shorebird Reserve Network from Manomet Center for Conservation Sciences--links to the Great Salt Lake and Mono Lake.

• See this ANTELOPE ISLAND MAP which you can purchase from  the UGS (Utah Geological Survey) DNR Bookstore and Map source - State of Utah or the Antelope Island Visitor Center - see other sites here.
  
• Get the Booklet: Geology & Antelope Island State Park, Utah, 1988. Other maps are listed in the Great Salt Lake Map Exercise. UGS (Utah Geological Survey) - Great Salt Lake Resources & Questions along with Publications. 
  
• Learn more from Ty Harrison, Professor of Biology, Westminster College of SLC. and the Great Salt Lake Project and other modules such as the Great Salt Lake Playa Foodweb Project. 

• More at: SELECT SOURCES, Northern Utah Wildlife, Utah.com, USFWS and learn about the modern land use conflicts from this document: Antelope Island Draft Access Management Plan - 2004 (PDF)