East Texas Earthcache #2: Down on the Bayou EarthCache

The Angelina River flows through  high quality bottomland hardwood habitat through this portion of the Pineywoods.  If you visit this area in the springtime, you will see that water fills the river channel and spreads out across the forest.  The plants here are adapted for this type of annual cycle.  The trees closest to the river channel and in the lowest spots can tolerate the most frequent and extensive flooding.  Trees that tolerate such flooding less are found higher on the slopes.  The pines are generally the least tolerant of flooding and they are found in the uplands.  Here at the Stephen F. Austin Experimental Forest, most of the other caches are found in the upland areas amongst the pines.

The easiest approach to the location of interest here will be via the Angelina River itself.  There is a public boat launch where Route 7 crosses the Angelina River.  The water moves pretty slowly here (if at all at some times of the year) and you may be able to return to this boat launch by paddling upriver.  If you're not up for that, you can certainly paddle downriver to the next public access point at US 59, but that's a pretty good haul.  You should be a strong paddler if you plan to do that in a day.  Otherwise, you may find it necessary to camp along the river between the access points.  The Texas Parks and Wildlife Department has some information about the river itself for paddlers.

There are two public hunting areas along the river.  They are the two units of the Alazan Bayou Wildlife Management Area.  The first you will find on the south side of the Angelina on your way to this cache.  The only access to it is by river and there are signs periodically nailed to trees along the river indicating public hunting.  The second unit of the Alazan Bayou WMA is past the cache by a few miles on the north side of the Angelina.

Some cachers might want to attempt this by hiking to it.  Be my guest.  It won't be the easiest approach and by my best guess it's a 4.5 terrain situation.  Trails and roads will take you most of the way from the parking lot, but the last mile as the crow flies (will certainly be much more than that as you fight through the brush and navigate around wetland areas) is all off-trail.  If you try it, start early in the morning, BE PREPARED, and be smart.  There are alligators in the river, venomous snakes, poisonous and painful plants, and sketchy terrain with the potential for deep mud, deep water, and getting lost.

Now that we've got the formalities taken care of, let's talk about river geology.

Wild rivers are characterized by the fact that their channels change from time to time.  The location you visit for this Earthcache is the confluence between the new river channel and an old section of river channel.  Can you tell which channel is new and which is old?

The first thing we want to look at will be the sediments visible on the banks of this river.  You will see that these sediments are mostly sands and silts.  Look at the banks here.  Do you see sandbars and other areas where sediment is being deposited?  Why or why not?  Take a handful of the sandy sediments along the river.  Rub them between your fingers.  Look at them under a magnifier (if you must, take some home where you can find a magnifier).  Are the grains coarse or fine?  Are they angular and sharp or rounded and polished?  What does this tell you about the environment these sands came from?  Do you think these sand grains were eroded from larger rocks in the mountains to the west?  Or do you suspect that they have a different source?  Considering our proximity to the coast, do you think these sand grains could come from a beach environment?

Look at the image of a generalized river to the right¹.  It describes the many features you will see (or will be unable to see) on this river.  In case you're unable to read the print on the image (you can enlarge it by clicking on it), I'm including the relevant points below.

• Runs are fast deep areas where the water surface is turbulent, but rocks do not break the surface.
• Riffles are shallow areas with faster flows where rocks break the surface.
  • Improves water quality by increasing dissolved oxygen, creates silt-free substrates.
• Boulders and Slabs are rocks with a diameter greater than 10 inches.
  • Critical habitat for many species; slows current to create eddies; provides resting, feeding, and hiding areas for fish, insects, mussels, and algae.
• Water is an essential part of stream and watershed ecosystems.  Both quality and quantity help determine the health of streams and their watersheds.
  • High flows flush out fine sediments

• Pools are wide, deeper areas with slow current that occur between riffle-run complexes.

• Woody Debris is dead tree material.

  • Helps protect banks from soil erosion; helps to reduce flooding impacts by slowing stream flows and forcing the current to scour deep pools, rebuild gravel beds; create runs, eddies, and clean sandbars; helps flush fine sediment into floodplains.

• Streamside Forests are wooded corridors along streambanks.  They often flood and naturally are often dominated by large overhanging sycamore trees [note: sycamores are uncommon in East Texas.  What common native species serve this purpose here?]

  • Improve water quality and quantity by providing shade, filtering out nutrients and pesticides, reducing soil erosion by stabilizing banks, providing a buffer area for fine sediment in upland runoff to settle out, and storing flood water that is slowly released to maintain base flows; improves aquatic habitats by providing woody debris, leaves, and other organic detritus which is an important link in the food web and nutrient cycling, undercut banks, deep pools, eddies, and other cover; helps create narrow, deep channels and islands; provides habitat for many mammals, amphibians, birds, and other wildlife; refuge for fish during floods.

• Meanders are bends in stream channels.  They are naturally formed as streams flow through floodplains.
  • Helps reduce downstream flooding by using the energy of water to create longer streams with more erosional and depositional areas; increases the quantity and quality of stream habitats.
• Islands and Bars are dry areas of land within the main channel of a stream below the ordinary high water level.
  • Create narrow, fast chutes, riffles, runs, high flow channels and backwater areas.
• Undercut Banks are edges of the streambanks that overhang the water.
  • Habitat for many species of wildlife
• Root Wads are large diameter underwater tree roots.
  • Help protect banks from erosion.

To log this Earthcache, please submit the following in an e-mail to me entitled "GC2H0WF: Down on the Bayou":

1. Which channel is the new river channel and which channel is the old one?
2. Please describe the sand in the sediments in this area.

Please include the following in your log:

1. Please take pictures of as many of the above listed river features as you can find and label them with the correct term when you upload them with your log.

¹ Sanders, R. E., Ed. (2000). A Guide to Ohio Streams: Ohio Chapter of the American Fisheries Society. Columbus, Ohio, Streams Committee: Ohio Chapter of the American Fisheries Society.