An Ancient Inland "Sea" EarthCache
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This is a two part Earthcache located on the sanctuary grounds of Audubon International. Sanctuary is open from dawn till dusk with plenty of parking and some very nice trails. Sorry but unfortunately the sanctuary grounds do not allow dogs.
It’s hard to believe walking around Albany and the surrounding area that millions of years ago this area was part of a great inland sea. Approximately 600 - 700 million years ago the North American continent developed a rift (a tear in the earth’s crust that continuously erupts magma and pushes the two sides apart) and began splitting apart, each side moving in the opposite direction of the other. As this occurred the area between the two land masses filled with sediments and volcanic deposits (from the magma at the rift zone). Over time sea level rose and much of New York was covered by an ancient shallow sea known as the Iapetus Ocean.
Once the rifting ended, the ancient sea began to close and our continent collided with the island arc that had developed during the rifting process. This event is called the Taconic Orogeny (or mountain building event). During this event the sedimentary deposits that made up the shorelines were scraped off and thrust onto the continent as the rest of the mass was forced deep into the earth.
New York State was part of this ancient inland sea approximately 400 million years ago. At this time New York and the present day North America were part of the ancient continent Laurentia which was located much closer to the equator. Due to its geographic location, New York’s Devonian climate was considerably more hot and humid, much like that in tropical regions today.
The bedrock in this area is part of the more widely known Heldeberg formation which consists of several distinct stratigraphic units of limestones, sandstones, shales and dolostones. Each unit represents a climate change and a variation in depositional environment from shallow seas with shifting currents to deep, calm, warm water environments. Each of these environments offers a window into what life was like in this area during each transition zone. The area of the initial point (I.P.) lies within the Onondaga limestone formation. This formation is highly fossiliferous – representing a deep water environment offering fossils of coral reefs and numerous vertebrates, cephalopods and gastropods.
Water flowing through the layers of limestone on the plateau above the nearby Heldeberg Escarpment (at John Boyd Thatcher State Park) has dissolved and eroded the rock, leading to a geological landscape known as karst terrain. The characteristic features of karst areas include caves, limestone pavement, sinking streams, sinkholes, complex underground drainage systems and springs. Limestone pavement is a natural karst landform consisting of a flat, incised surface of exposed limestone that resembles artificial pavement.
Conditions for limestone pavements are created when an advancing glacier scrapes away overburden and exposes horizontally-bedded limestone, with subsequent glacial retreat leaving behind a flat, bare surface. Limestone is slightly soluble in water, so corrosive drainage along joints and cracks in the limestone can produce slabs called "clints". This area is also a wonderful environment to see first hand the action of physical weathering of a stream bed. When the water rises and the stream is running it carries with it sand, pebbles, rocks and sometimes small boulders. As these are carried along with the stream they crash into one another and they are broken up and rounded by the abrasive environment.
The Hollyhock Hollow Nature Sanctuary contains several of the features described above. So, WHY have we told you all of this background information? You will need to read through the information given above to answer the following questions. This is where the fun starts – we get to climb on the rocks and play a little.
PART 1 N42° 32.488 W073° 52.422. At the I.P. search the surrounding area for the rocks that have fossils in them – be careful to check your footing as you climb around on the rocks. Once you find some fossils – pick your best one (they may show up a little better if you wet the rock a little) THEN, to claim credit take a picture of your GPS next to at least ONE fossil. Take it nice and close up so we can see the fossil.
Please be careful to check stream conditions – although this is a fairly low level, dry stream bed much of the time – the stream can rise rapidly with rains - if there is enough water where you need to wade into the stream at all, DO NOT ATTEMPT THE CACHE – come back another day OR take a picture of the high water level and do the alternate cache listed below.
PART 2 N42° 32.565 W073° 52.515. Once you reach this waypoint take a look around you. The rocks around you are very different in appearance from each other. Give a brief description of what the difference is and how you think it occurred. HINT - look at the stream bed vs. the rocks laying on and around the stream bed - physically they look different in shape. Then, post a picture showing the contrast between some of the rocks shapes.
Remember - this is for fun, NOT a test to stress over - give it your best guess, don't worry about it being right on target.
As with all of our Earthcaches, we aren’t looking to delete smiley’s for wrong answers. Just read through the material, use your own interpretative skills and take a stab at it. Remember to POST your two (2) pictures to the webpage and EMAIL the answers (don’t post the answers).
ALTERNATE CACHE: If the conditions are not safe do the following to claim credit for the EC:
1) Take a picture of the high water level at the IP
2) Do the nearby "The Brooklyn Bridge Starts Here?" Cache (Stage 1 located at N42° 32.787 W073° 52.293). At the final you will see a rock formation nearby. These rocks are the same formation found along the streambed IP. Look around the rocks and find some fossils.
Take a photo of at least ONE fossil with your GPS next to it. Nice and close so we can see the fossil.
Enjoy the surrounding preserve and the other nearby caches while you are here, and most of all HAVE FUN!!
Although we read through everyone's answers on all of our EC's we are not able to respond to each one individually. We hope you enjoy this Earthcache and maybe even learn something new about the world around us.
Additional Hints
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Treasures
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