Pit/Mound Topographic Adventure
Coordinates … N 42° 15.350 W 078° 41.662 / Ending … N 42° 15.310 W 078° 41.575
EARTHCACHE REQUIREMENTS
Each cacher must send his/her own answers to log a find. … “Geocachers must complete the tasks before they log the EarthCache as found.” (4.3. EarthCache logging tasks)
Enjoy the journey (learning adventure) as well as the destination (smiley earned). Remember to take only pictures and leave only footprints. To get credit for this Earthcache, complete the following tasks:
NOTE: Answers via message -and- log signature picture are required to post a find for this cache.
1. MESSAGE …. Based on the reading, what is the main cause of pit/mound topography?
2. MESSAGE …. Select a pit. Reach down and feel the soil. Describe both what you see and what you feel..
3. MESSAGE …. Select a mound. Reach down and feel the soil. Describe both what you see and what you feel..
4. MESSAGE …. Select an undisturbed area. Reach down and feel the soil. Describe both what you see and what you feel.
5. THE MYSTERY …. There are a myriad of fallen trees between the posted coordinates and the waypoint coordinates that occur only along the wooded section of the road. The opposite side of the road is meadow with no apparent affect. What do you think caused all these uprooted trees in this short section of the forest. The posted picture shows the roots to be relatively shallow. Did construction of the road disturb the root system allowing for high winds to topple them? Then why are the trees only uprooted in this small section of roadway? Or is this because the bedrock is close to the surface preventing a deeper root hold? But again, why are the trees only uprooted in this small section of forest? Perhaps the answer lies in the soil, or the water table. Your explanation (hypothesis) can be scientific or creative.
6. LOG … Take a picture of you or your signature item with any of the fallen trees. This is your log signature.
FORMATION OF PIT AND MOUNDS
Pits and mounds might be considered the charismatic microtopography of the forest. These features, vividly nicknamed ‘pillows and cradles,’ are formed by the uprooting of trees. In most forests, these features contribute important habitat diversity while varying soil processes. The pit is formed where root mass and attached soil used to be, while the mound forms from the soil and roots that were pulled out of the ground.
SOIL DIVERSITY
Mounds tend to erode and thus are more unstable than the forest floor or the pit. The surface of the mound also contains very little organic matter because it is mainly soil that was uprooted from the mineral horizons of the soil layer.
Pit and mound micro-relief resulting from trees uprooted by windthrow could have regimes of microclimate and soil features that differ from areas of undisturbed soil. Soil does vary with the three microsites associated with pits and mounds … pit bottom / mound top / undisturbed area.
UPROOTED TREES
When wind speeds are excessive, storms can cause entire trees to uproot. This is more likely to occur when soils are wet and the tree’s roots are unable to securely anchor themselves in the soil.
Amid heavy rains a surge of fluid, or sap, is drawn up into the canopy making the tree top-heavy and prone to toppling. A large and healthy root system is crucial for a single tree, a small group of trees or a line of trees to survive a high wind event or fluctuations in sap levels.
These uprooted trees are the cause of the pit/mound topography seen in forests.
RESOURCES
Google … Windthrow Events … Jamestown Audubon Pit and Mound Earthcache … The Pit and Mound Cache
ANSWERS
- Uprooted trees
- PIT … cold, wet, smooth
- MOUND … warm, dry, gritty
- UNDISTURBED AREA … The area I chose was actually both seen and felt to be between the attributes of the pit and the mound. Interesting!
- Answers vary
To the south is a meadow that is relatively flat. To the north is the forest with the fallen trees at the edge. It is more of a rolling topography.
There are 16 fallen trees along the road only in this section between the posted coordinates and the waypoint coordinates. I believe there was a microburst that blew across the meadow uprooting the trees along this section of the road.
REVIEWER NOTES
Are wind microbursts known in the area? Or, alternatively, is the more prevalent treefall along the road caused by disruptions of the topsoil by the road installation, changes in water access to the root systems (compacted ground, road serving as a dam, etc.) that could drown some roots and/or dry out others?
Also, fallen trees fall into the category of botany or forestry unless the EarthCache page is able to bring in an EarthScience lesson. Reference the Knowledge Books at https://www.geocaching.com/help/index.php?pg=kb.chapter&id=51&pgid=295 .
The photo on the EarthCache page leads me to believe that the roots for these trees are fairly shallow. Is this due to bedrock not being very far below the surface? Or, another type of soil transition? Or, high water table? Or??? Logging tasks #2 and #3 indicated there is some sort of transition in soil type as one goes deeper below the surface.
In some forests containing trees with shallow roots, adjoining trees interlock roots for increased stability. If a road or plot of land is cleared of trees, the interlocked matrix is disturbed and a domino effect of additional falling trees can be observed following a wind storm or other event. Is it possible that is what is happening here?