Black Rock is a nearby neighborhood of Buffalo, NY. It was named for a large outcroping of limestone and black rock that was blasted away during the building of the Erie Canal. At the posted coordinates underneath the bridge you will see limestone remnants with dark, blackish brown deposits throughout them. These deposits are known as chert.
WHAT IS CHERT?
Chert is a microcrystalline or cryptocrystalline sedimentary rock that is made of silica(SiO2). It forms with certain particles accumulating in bodies of water. These particles are skeletons of plankton. When the plankton die, they sink to the bottom of the water and accumulate into sediment called ooze. Chert once was a siliceous ooze made of plankton like diatoms and radiolarians. Siliceous ooze turns to chert by going through a slow process. The processes of lithification and diagenesis are how the sediments become chert.
LITHIFICATION (conversion to rock) It begins when sediment is laid down and becomes gradually buried and compressed under new sediment.
DIAGENESIS is the process by which sediment undergoes physical and chemical changes during its lithification on its way to become chert. Compaction, leaching, cementation, and recrystallization are forms of diagenesis.
Chert has a waxy luster, a concoidal fracture(shell shaped), smooth texture, and a hardness of 7 on the Mohs scale. Thats harder than steel! Chert occurs in various colors due to trace elements in the rock. Colors can be red, black, brown, green, white and gray. Ancient cultures used it for tools, axes and arrowheads since the edges are very sharp.
Common Varieties of Chert
TO GET CREDIT FOR THIS EARTHCACHE you must message or email me the following observations and answers:
1.) Observe the deposits of chert in the limestone rock and describe any shapes you see.
2.) Run your hand over the chert specimen and compare it to the feel of the surrounding limestone. Describe what you felt.
3.) Refer to the 'COMMON VARIETIES OF CHERT' chart above and determine which variety you are observing at this earthcache location.
4.) According to the write up, what is ooze?
AS YOUR LOG SIGNATURE, upload a photo to the cache page image gallery of yourself (or your signature item) standing on top of any boulder that is lining the road.
CONGRATULATION to The_Geocaching_Ninja for being FTF.
