ROCK CITY PARK
Adults $5.00 / Seniors $4.00 / Children 6-12 $3.00
Open Memorial Day to Labor Day from 9 to 5
THIS IS SEASONAL, BUT KEEPING IT ACTIVE FOR THOSE PLANNING A VISIT.
THANK YOU Cindy Smith (Park Director) and Dale Smith (Park Ranger) for permission to share this earthcache site.
THANK YOU University of Pittsburgh Bradford for the educational guide.
Enjoy your stroll and learning adventure as you wind your way around "gigantic rock formations".
EARTHCACHE REQUIREMENTS
Each cacher must send his/her own answers BEFORE logging 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:
ANSWERS ... SEND ALL ANSWERS VIA MESSAGE
LOG ... INCLUDE ON-SITE VERIFICATION PICTURE WITH REASON FOR YOUR CHOICE
1. ON TOP OF THE CLIFFS ... a. Explore and find the widest crack. Using your compass, determine the direction of the crack. / b. Explore and find the narrowest crack. Using your compass, determine the direction of the crack./ c. Explain why the cracks formed in different directions..
2. DESCENDING ... a. As you descend the iron stairs, look at the rocks. Describe changes in the depositional layers. / b. Where did the major amount of eosion of the sandstone occur - top / middle / bottom?
3. WEATHERING INDICATOR ... This area has a lot of name carvings. Using your compass, the carvings that are most easy to read are located on a rock face that points to North, South, East, or West? Explain.
4. RIVER SYSTEMS ... The whole complex of rocks in this park is a result of depositions by the river system that flowed through this area. Based on your observations and reading, is the river system meandering or braided? Explain.
5. ORIGINAL HORIZONTALITY ... a. View the front of Teepee Rock. Do all the strata on the face of this rock appear horizontal? What does that indicate in terms of deposition and movement via geological procesess? / b. View the side of Teepee Rock. Focus on the base of the rocks on the right side of the tunnel. Does the strata still appear horizontal? If not, explain why.
6. ROCK CREEP ... a. Measure the space between the two rocks on the left. Calculate how long it took for that space to occur. / b. Measure the space between the two rocks on the right. Calculate how long it took for that space to occur. / c. How will rock creep affect The Old Man -and- the Monkey (both are visible in the rocks)?
7. CROSS-BEDDING ... a. At what angles are these cross-beds dipping? / b. What does that tell you about the paleocurrent?
8. WEATHERING AGENT ... a. What impact do these trees have on weathering the rocks. / b. What other signs of biological weathering are present at this site?
9. DIFFERENTIAL WEATHERING ... a. Observe Balancing Rock. What differences are evident when viewed from different sides of the same rock? / b. Observe Anvil Rock. What differences are evident when viewed from different sides of the same rock?
10. STRATIFICATION MYSTERY ... a. Observe the stratification at N 42° 01.083 W 078° 28.672. What caused formation of these tilted layers? Does it appear like it will continue this way to ground level? / b. Observe the stratification at N 42° 01.087 W 078° 28.660. Does what you thought for "a" still hold true? Explain.
11. HONEYCOMB WEATHERING ... Are the “pock marks” on the surfaces primary or secondary structures? How do you know?
12. STAINING ... a. What color staining is visible on the rock at N 42° 01.084 W 078° 28.567? What caused this staining? / b. What color staining is visible on the rock at N 42° 01.057 W 078° 28.686? What caused this staining?
LOG ... Post a picture of you or your signature item at your favorite place along the trail. Include reason for your choice.
OPTIONAL - Please respect the time and effort involved in creating this earthcache by adding A and B to your log.
A. JOURNEY OF THE MIND ... Science explains what we observe. Relate (in your own words) something you found interesting in the reading. This adds to your learning adventure and your log.
B. JOURNEY OF THE HEART ... Art shares our personal experience of what we see. Share something special you found on site, and why it is special to you. This is a memorable addition to your log and will make other hearts smile.
Journeys of Heart and Mind ...
Stories to Touch the Heart and Puzzles to Challenge the Mind / Rainbow Tree Story
ON TOP OF THE CLIFFS
Through weathering and erosion, cracks (called joints or fractures) developed in the rocks, forming blocks that either slid downhill or were held in place by the valley walls. The widest cracks developed parallel to the valley forming blocks that slid downhill enlarging the cracks. The narrowest cracks developed perpendicular to the valley forming blocks that were helld in place by the sides of the valley.
THE VALLEY
DESCENDING
The two main types of rocks you see at Rock City Park are conglomerate and sandstone. Both sediments were deposited together, in alternating sequences. Sandstone is the softer rock and is weathered more compared to the harder conglomerate. This entire area was once a river system, so deposition and undercutting along the banks was prevalent. Erosion of the sandstone will result in gaps, crevices, etc. indicating that sandstone was once deposited in the area. Although it is called The Olean Conglomerate, the sandstone in this particular place is the dominant type of rock.
WEATHERING INDICATOR
The Temperature in the shade isn't cooler than the temperature in the sunlight. In the shade, you may feel 10-15 degrees cooler, but the temperature is the exact same as the temperature in full sunlight. Shade only feels cooler because you are avoiding solar radiation. The rocks, however, are a different temperature in the sun than in the shade due to the amount of solar radiation thay are absorbing. Those in direct sunlight expand as they heat, whereas the interiors and shaded areas do not. Differential expansion and contraction produces stresses which can result in cracks and physical weathering. Also, there is a difference in weathering due to moisture. The sun exposed faces have less mositure than the sun shaded faces. The more moisture a rock retains, the more favorable environment it is for the growth of biological organisms, These organisms contribute to mechanical erosion by widening cracks, and to chemical erosion due to the acids produced.
VISUAL CLASSIFICATION CARVED LETTERING ... Meierding
Lettering is sharp and distinct / Lettering is slightly rounded but still legible and clear / Lettering is legible but rounded with some edges clearly removed / Lettering is rounded with all or most original edges removed. It is still legible, but becoming more indistinct from the surface of the grave / Lettering is still just about legible, but now almost indistinguishable from the surface of the gravestone / Lettering has virtually disappeared
RIVER SYSTEMS
"Meandering rivers typically only contain one channel that winds its way across the floodplain. As it flows, it deposits sediment on banks that lie on the insides of curves (point bar deposits), and erode the banks on the outside of curves. When the river floods, it deposits fine-grained material on the floodplain. As the floodplain is a lot larger than the channel, deposits of meandering river systems are dominated by fine-grained material; coarse-grained channel deposits tend to be relatively minor." The bed of meandering rivers is narrow. If the rock record shows individual channels, you are observing a meandering river system.
"Braided Rivers exhibit numerous channels that split off and rejoin each other to give a braided appearance. They typically carry fairly coarse-grained sediment down a fairly steep gradient. As flow regimes in a river vary, braiding is developed by the systematic sorting as the stream deposits load sizes it is no longer able to carry. This bedload deposition will result in a number of different types of bars and bedforms, which inturn impede and divert the flow. Banks which are easily eroded will facilitate this process" The bed of braided rivers is wide. If the rock record shows multiple criss-crossed channels, you are observing a braided river system.
ORIGINAL HORIZONTALITY
Teepee Rock is actually a fragment of a larger boulder tilted on its side. Since all sediment formations are deposited horizontally, vertical strata and rotated cross-beds indicates the rock is not in its original position. Since this area was unglaciated, the boulder probably reached its current position via movement due to gravity.
ROCK CREEP
The Three Sisters rock formation was originally a single rock. "Most likely the break, and erosion of it started with the freeze-thaw processes. It began to creep because the blocks of sandstone sit on shale, and on a slope – those are good combinations for the slow downhill creep of the blocks." Use 1/16" per year to calculate how long it took to create the openings you are measuring.
CROSS-BEDDING
Cross-bedding aka cross-stratification is layering at an angle to the main bedding plane. Cross-bedding forms during deposition on inclined surfaces such as ripples. The original depositional layering is tilted indicating that the despoitional environment contained flowing water.
Cross-beds can tell geologists much about what an area was like in ancient times. The direction the beds are dipping indicates paleocurrent, the rough direction of sediment transport. The type and condition of sediments can tell geologists the type of environment (rounding, sorting, composition). The inclined layers (foresets) are deposited at an angle allowing geologists to measure direction of the cross-bedded sediments (dip) and calculate the paleoflow direction. A shallow angle of cross-beds represents slower water speeds. A steep angle of cross-beds represents faster water speeds.
Sentinel Rock is the largest free-standing rock in the park estimated to be 50+ feet.. This large conglomerate boulder was once part of the main outcrop, but slowly slid downhill along the contact with the shale visible along the path. Here you can see multiple sets of cross-bedding.
WEATHERING AGENT
Living organisms contribute to mechanical weathering through the growth of roots or the burrowing of animals. Tree roots grow into cracks and joints, increasing the surface area for continual weathering by plants, wind, and water. Plants give off organic acids as part of their life and decay processes. These acids help to break down rocks chemically. Decaying remains of dead animals in soil may form organic acids which, when dissolved in water, cause chemical weathering. VASCULAR PLANTS are larger and grow out from the rocks. The evidence that some soil is present is found in the plants which appear to be growing "out" of the rock. In reality, these plants have roots that are growing in soil that is located in the cracks of the rock. NONVASCULAR PLANTS are smaller and cover surface of rocks. Lichens and mosses grow on essentially bare rock surfaces and create a more humid chemical microenvironment. The attachment of these organisms to the rock surface enhances physical as well as chemical breakdown of the surface microlayer of the rock. ANIMALS burrow and disturb the soil layer adjacent to the bedrock surface, thus further increasing water and acid infiltration and exposure to oxidation processes.
DIFFERENTIAL WEATHERING
Weathering that occurs at different rates as a result of variations in composition of a rock. This results in an uneven surface where more resistant material protrudes above softer or less resistant parts.
STRATIFICATION MYSTERY
The layered rock structure is due to changes in deposition of sediment. This is a result of several factors. One is the type of sediment deposited. Another is due to fluctuations in the depositional agent, in this case river currents. THE MYSTERY ... Observiations from different perspectives often causes a change in the way we think.
HONEYCOMB WEATHERING
These are natural erosional features developed over thousands of years by rain water. When a drop of water stays suspended on the surface of an overhanging pebble, the water will produce some chemical erosion to the cement surrounding the quartz pebble. In time, millions of rain droplets will erode the cement surrounding the pebble causing it to fall, and leaving behind an indentation. These indentations represent an increased surface upon which water and other elements can act and continue to erode which enlarges their indentation. Primary sedimentary structures are produced at the same time as the sedimentary rock in which they occur. Examples include stratification and cross-bedding. Secondary sedimentary structures form after deposition.
STAINING
Most sedimentary rocks contain iron in varying degrees. This mineral may appear in patterns or dispersed randomly throughout the parent rock. Pyrite and pyrrhotite, predominantly reddish in color, are quickly decomposed by chemical weathering forming the iron minerals hematite and limonite. These minerals impart stains of red, orange and brown to the rock surface. Iron sulfate minerals also form and impart cream colored to yellowish stains. Manganese also causes black staining on rocks when it is exposed to air and water. Biological organisms cause staining due to chemicals released in their daily life-sustaining activities.
RESOURCES ... Rock City Park ... University of Pittsburgh Bradford Educational Resource Guide