This Earthcache is accessible via boat via the Trent-Severn Waterway, OR by foot, across the foot bridge at lock 11 and then down the stairs to the viewing area. While the area is beautiful it can be quite dangerous, please obey the lock master when crossing the lock bridge or when entering or leaving the lock by boat. Always pay attention to wind and weather patterns before heading out and make sure you have all of the appropriate safety equipment with you at all times if you are choosing to access this by boat. you do NOT need to access by boat in order to log this Earthcache, but it would allow you a better "up close and personal" look of the limestone vs accessing on foot from lock 11.
Trenton Limestone
Many millennia ago, glaciers covered all of this area. Eventually the glaciers melted and they formed The Great Lakes. In the process, large deposits of sand were left behind. In Lake Ontario, the sand was eventually carried along by currents until it hit pre-glacial limestone outcroppings as seen at GZ. These limestone outcroppings were remnants of ancient sea beds.
So what is an outcrop? An outcrop consisting of several horizontal sedimentary rock layers represent a vertical time-series of geologic events. The textures of each sedimentary layer tells us the environment that was present at that location when the layer formed. Geologists use these textures to define the rock layer as a facies. If the environment changes, a new layer of sediment possessing a different texture will be laid on top of the existing layer.
The Trenton consists of limestone that becomes increasingly dolomitic, and in places it is completely dolomitized. The Trenton is tan to light tannish gray to medium tannish gray. The color variation in the limestone is due to the variation in the content of skeletal grains versus micrite; the darker color correlates with the higher micrite content. In the dolostone, the size of the crystals appears to be the controlling factor; the more coarsely crystalline phases are lighter colored.
The Trenton Limestone has a maximum thickness of 265 ft (81 m) but is commonly seen in much thinner layers; in this area, it consists primarily of black or dark bluish-grey limestone, rich in fossils, with thin shale beds separating limestone into beds ranging in thickness from 3 to 30 cm. Closer to the top, the proportion of shale interstratifications increases. There are also zones of recrystallized limestone, generally without shale interstratifications; these areas are thin and located at the base of the group. The Trenton Group limestone is sometimes highly bituminous.
So where did this limestone come from? Limestone is a common type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate(CaCO3). Limestone forms when these minerals precipitate out of water containing dissolved calcium. Limestone hardness can be affected by the amount of calcium that is dissolved, as well as different mineral components when each layer of limestone is formed. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. The outcrops in the area were formed over millions of years through a process of differential erosion of these rocks of different hardnesses. Through time the soft rocks weather away or erode by the action of streams. The gradual removal of the soft rocks undercuts the resistant caprock, leaving a cliff or escarpment. The erosional process is most readily seen at Niagara Falls, where the river has quickened the process.
In order to log this cache as found, please answer the following questions from the water (on a boat, as swimming would be extremely dangerous) or by standing on the lower level platform next to lock 11, down the stairs from the lookout platform. Answers can be sent by email or by message to Pasha88. You do not need to wait for an answer before logging, but if answers aren't received within 3 days of logging your log may be deleted.
1. Estimate the height and width of the limestone cliff in this location, from the water level to the top of the cliff and from the northwest to the southeast edge of the outcrop.
2. Do you see any areas where signs of erosion or weathering are evident? Examples may be: exposed roots of trees or other foliage, cave-like areas that have been formed at or near the water level, evidence of recent land slides where pieces have broken off and fallen into the water below, etc.
3. Approximately how thick are the limestone layers in this area? Approximately how many layers do you see? Is this consistent with Trenton limestone as described above?
4. Take a mandatory photo of yourself or your GPS or signature item with a section of the limestone cliff OR with nearby Lock 11. You do not need to show your face, but each Cacher needs their own photo attached to their log to show their visit to the site.
I do not expect PhD thesis level answers, but please make an effort to answer the questions to the best of your ability. Any logs without a photo will be deleted.
Stay safe and have fun - remember that a smilie is not worth risking your life for.