PERMISSION:
This Earthcache was placed with permission of the Deputy Chief, Interpretation and Education of Shenandoah National Park.
EARTHCACHE REQUIREMENTS:
Each cacher must send in their own answers when logging this find. After you arrive at this creation of nature, enjoy the geological features and what you will bring home with you through this experience. Review the materials below and message/email your answers to questions to the best of your ability. Please follow all logging requirements and do not post any answers in your log. Please stay on the trail to locate the Earthcache.
There is an entry fee to enter the Skyline Drive.
ABOUT STONY MAN TRAIL:
Stony Man Trail and Appalachian Trail share the same trail for a short distance. There are several different approaches to reaching this Earthcache location. The parking coordinates listed will put you with the shortest hike to reach it. Blaze markings on the sides of trees along the trail are either BLUE for trails, WHITE for the Appalachian Trail. The Stony Man Trail is a blue blaze. After you complete this Earthcache, be sure to venture on to the summit of Stony Man which has incredible views.
The Rock and Hard Place:
As you travel, hike and spend time in the Shenandoah National Park. You will notice a variety of rock formations and other vegetation, including a variety of trees. Though this rock's formation journey began millions years ago, this yellow birch tree's journey has been about 75 years or so.
What is Biological Weathering?
Weathering refers to any process by which a rock is broken down, generally at surface level. Biological weathering refers to weathering caused by organisms such as plants, fungi, bacterial microorganisms or animals. It can be either physical or chemical. Biological weathering can work with physical weathering by weakening the rock or exposing it to physical forces or chemical weathering. Not all biological weathering is visible. Many Microorganisms in the soil or on the rock's surface can contribute to this. Many types of bacteria obtain their nutrition through taking a combination of nitrogen from the surrounding air as well as minerals. These minerals may include silica, phosphorous and calcium from the rock. The rock is weakened from this removal and is further vulnerable to the forces of nature by wind and water. Lichens that grow on rocks also contribute to weathering by breaking down the minerals in the rock, using them for their own nutrition.
Weathering is a natural process that causes the breakdown of rocks into smaller rock particles or new minerals. Weathering is the first step in the erosion process, breaking down the three major rock types round near the Earth's surface: sedimentary, igneous and metamorphic.
Weathering is a natural process that causes rocks to break down into smaller rock particles or new minerals. Weathering is the first step in the erosion process, which breaks down the three major rock types found near the Earth's surface: sedimentary, igneous and metamorphic.
This rock began the process of cracking through freeze/thaw weathering. Water will expand 9-10% in a frozen state. This makes the freeze/thaw cycle incredibly powerful. As water seeps into these tiny cracks and freezes, the expanding force of the ice created from freezing will cause the rock to crack a bit more. With each future freeze/thaw, this crack will become longer and wider due to the wedge action of the water as it freezes. Through this mechanical process over a vast number of years, the rock continues to split as the increasing volume of water that is able to seep into the crack, freezing and thawing, expanding the crack.
The crack in the rock is large enough that it allows other environmental actions to begin. The wind blows, other trees may fall in the area, dust and dirt become airborn and small animals may visit this inviting split in the rock. Soil eventually collects and is enough to support a seedling. A seed from another tree, probably close by, is transported to this very spot either through the wind, another animal or a bird. The seed settles in the soil that rests inside this crack and the tree's journey begins.
A Tree Begins:
Gravitropism or geotropism is growth in direct response to gravity. Gravitropism is important for plants as it directs the growth of roots toward the pull of gravity (positive gravitropism) and growth of the stem in the opposite direction (negative gravitropism). The orientation of the root and shoot system is observed in germination stages as a seedling. The embryonic root is released from the seed, growing downward in the direction of gravity. If the seed were turned with the root pointing upwards from the soil, the root sould curve and reorient itself back in the direction of gravitational pull. In addition, the developing shoot would orient itself against gravity and grow upward.
The seed begins with a tap root, allowing for stability and absorption. With time, other roots will outgrow the tap root. Normally tap roots will not continue to grow deeper as deep soil does now hold the amount of oxygen and nutrients that the root needs in order to survive. As a result, the other roots that emerged through the growth of the seedling and tap root will play a key role in the tree's future longevity.
There are four general types of roots beyond the tap root.
Lateral Roots grow outwards under the soil's surface. They absorbs water and nutrients to keep the tree growing and healthy as well as anchoring the tree.
Oblique/Heart Roots grow on the diagonal and have the same function as lateral roots.
Sinker Roots grow downwards from the lateral roots to a depth of several feet. At that level, the lateral roots are able to take advantage of additional water and nutrients present deeper in the soil. This also allows for greater tree stability.
Fine Roots give rise from all the root types which is the site of direct absorption of water and nutrients. The fine roots also house mycorrhizae, creating a fungal partnership that assists in the roots better ability to absorb water and nutrients.
Plant Tropisms:
Plant tropisms are mechanisms by which plants adapt to environmental changes. A tropism is a growth toward or away from a stimulus. In the case of this tree, it is the rock that is the stimulus. Common stimuli that can affect growth, not just this tree, include light, gravity, water and touch. Plant tropins differ from other stimulus generated movements, such as nastic movements, in that direction of response depends on the direction of the stimulus. Plant tropins are the result of differential growth. This type of growth occurs when the cells in one area of the plant, such as the root or stem, grow more quickly than cells in the opposite area. Differential growth of the cells will dirrectly affect growth of the stem or root and will determine the directional growth of the entire tree.
The Process Continues:
As you continue your study of this interesting rock and root system, understand that this is an ongoing process. The freeze/thaw process continues, as well as the growth of the tree and root system itself, to break this rock apart. Who knows how long this will take, but in the meantime, each of us can enjoy this marvel of nature's work and how things continually evolve through time.
QUESTIONS TO ANSWER:
1. What angle is the rock as compared to the tree?
2. What forces of nature have influenced the appearance of the rock?
3. How much do you think the rock has cracked due biological weathering?
4. How much do you think the rock has cracked due to physical weathering?
5. Does the rock, as a whole, appear completely cracked apart AND is it happening on other areas of the rock not directly affected by the tree's roots?
6. Please post a photo at or near the site. You do not have to be in the picture unless you want to. This is your log signature.
GINGIN'S MESSAGE:
S - Shenandoah, oh Shenandoah, our place of peace, reflection and happiness
T - Treasures for our hearts, overjoyed just through the sights of wildlife, a vista and sharing with those with us
O - Ongoing comfort that brings us home having experienced time in these incredible mountains
N - Nothing from our time here should be anything less than a peaceful memory of good times
Y - Yet we know, our responsibility to this land is how we impact it during our time there.
M - Mankind's travels should be kept on the trails,
A - All wildlife, in waters, land or sky, call this land their home...we are just visitors
N - Never disturb wildlife, pick flowers or damage anything here to maintain it's unparalleled beauty.
T - Time is always short, enjoy every moment you can during your time in the Shenandoah
R - Respect these mountains to preserve them for generations not yet born to enjoy
A - Always leaving just your footprint only, taking photos and memories home, nothing else
I - In all cases, pack in-pack out, recycle, pick up any litter you come across
L - Love the Shenandoah National Park.....renewal, refreshing, envigorating, enjoyable, peace.
REFERENCES:
Geology Along Skyline Drive by Robert L. Badger, 2012, ISBN 0-931606-28-1
Stony Man Trail, Robyn Nolen, 2015 (Shenandoah National Park publication)