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". If you have all the required pictures, see Cindy or Dale for a special gift.
NOTE: Need a protractor to measure the angle cross-beds are dipping.
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:
1. MESSAGE …. a. At what angles are these cross-beds dipping? / b. What does that tell you about the paleocurrent?
2. MESSAGE …. How much time did it take for all this sediment to be deposited by the river?
3. MESSAGE …. Compare the angles of the cross-beds at Sentinel Rock with those of Pulpit Rock. a. Are they the same? / b. What does that tell you about the paleocurrent?
4. LOG …. Post a picture of tabular cross-bedding anywhere along the trail. This picture is your log signature.
5. LOG …. Post a picture of trough cross-bedding anywhere along the trail. This picture is your log signature.
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
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.
Tabular cross-bedding aka planar bedding consists of cross-bedded units that are extensive horizontally. Trough cross-bedding, on the other hand, consists of cross-bedded units that are curved, and thus limited in horizontal extent.
RATE OF SEDIMENTATION
A normal sedimentation rate of gravel and coarse sands is 10 cm/1000 years, so 3000 years/ft.
SENTINEL ROCK
This 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.
RESOURCES ... Rock City Park ... University of Pittsburgh Bradford Educational Resource Guide