To log this Earthcache as a find, you must visit each of the 5 reference points (also listed below) and answer the questions associated with each one. They can be done in any order, however, I have included them in the order in which I walked it. The hike here will be less than 300m in total, however, it can be very dangerous. I would definitely recommend this Earthcache for kids, but please keep them close. There are many unseen dangers (especially in the winter) below your feet such as sinkholes and cave windows. Please feel free to upload any pictures that you take on your adventure, but please remember not to include any spoilers. Any logs that contains spoiler pictures will be deleted. Please email me with the answers to the questions, and log as a find. I will delete logs where the incorrect answers have been sent.
1. Posted Coords N 43° 11.073 W 079° 47.727 At the opening of the cave, what evidence can you see of development in the area? Upon entering the cave, how many distinct levels of rock do you see directly to your North? Estimate the size of this cave. This may require you to travel a bit further into the cave. Upon leaving the cave, go and stand on the top of the cave, directly North of the opening. What are some of the markings that you can see below your feet?
2. Olmsted Cave Window N 43° 11.079 W 079° 47.736 What is the shape of the opening to this karst window? How deep is it? What could have caused it? Describe the texture of the wall (may need flashlight).
3. Solution Shaft N 43° 11.096 W 079° 47.726 What was the purpose of this solution shaft? Approximately, how deep is this shaft, and how wide?
4. & 5. Suffosion Sinkhole A N 43° 11.097 W 079° 47.723, & Suffosion Sinkhole B N 43° 11.097 W 079° 47.726 Compare Suffosion Sinkhole A with Suffosion Sinkhole B in terms of size, specifically referring to depth. What could have caused these differences?.
6. From the suffosion sinkholes, walk another 20m North along the trail and describe what you see. Please use geological terms if possible.
Olmsted Cave is situated at the south end of a woodland that extends to Highland Road. This woodland and the storm water management pond to the south are part of Hamilton Park owned by the City of Hamilton. It is NOT a part of the Eramosa Karst Conservation Area, even though it contains many karst features, the area surrounding Olmsted Cave has been developed, and has negatively impacted this unique geographical feature. Olmsted Cave is the second biggest cave in the Karst Region.
A number of other areas in Ontario have single sinking streams and springs, and some areas have two or even three sinking streams in close proximity. What distinguishes the Karst area is the large number of sinking streams and associated karst features. As a result of urban development in 2000, one of the prominent sinking streams, Upper Olmsted Creek, has been diverted into a storm sewer and no longer sinks in Olmsted Cave.
Olmsted Cave was probably the principal recharge point for Olmsted Spring. Recent urban development has redirected runoff in the former Upper Olmsted Creek watershed to storm sewers and there is no longer any surface runoff sinking at Olmsted Cave. Although flow in the Olmsted karst system has been greatly reduced as a result, there is still some flow emerging from Olmsted Spring, indicating that it still receives some diffuse recharge, or possibly some allogenic recharge from other sinking streams. Olmsted Cave is an important component of the Olmsted karst. It has a relatively large, scenic entrance, although the cave itself is not especially long. The main entrance is a vertical shaft about 3 metres deep. Prior to recent construction, Upper Olmsted Creek sank in the entrance, flowed across the floor of the cave and sank in breakdown slabs and silt covering the floor. The flow from the former Upper Olmsted Creek watershed is now directed into storm sewers. If the capacity of the storm sewer and storm water management pond is ever exceeded, then the overflow will drain into Olmsted Cave. Next to the main entrance of Olmsted Cave, there is a long narrow slot that forms a karst window.
A karst window is a rock-walled depression, usually with vertical walls, with a stream flowing across its floor from one side to the other. Typically they are created by collapse of a bedrock roof into an underlying cave passage. Olmsted Cave has about 30 metres of passage with a shaft entrance and a long skylight entrance developed along a prominent vertical joint. The remaining two caves are small. Each drains an area of just a few hectares and the stream passages in the caves are correspondingly smaller in size, being about 20-30 centimetres in width and effectively impassable to humans.
There are several karst features situated in the woodland to the north of Olmsted Cave. These are all contained within Hamilton Park. A broad, shallow valley extends from Olmsted Cave to Highland Road. It is an excellent example of a dry valley. About 30 metres to the north of Olmsted Cave, a tiny stream sinks in an excellent solution shaft. This shaft probably leads to the unexplored extension of Olmsted Cave, and the various solution shafts may have acted as overflow sinks. Debris at the base of the shaft prevents further exploration. Further to the north, there are a number of suffosion sinkholes developed along the dry valley. Prior to recent construction, Upper Olmsted Creek sank in Olmsted Cave and flowed in the subsurface for a distance of 380 metres to Olmsted Spring. The unexplored cave or conduit is probably at a depth of 5 metres or more for most of its length. An approximate minimum depth of this passage could be deduced by an accurate leveling survey at the cave and at the spring. Upper Olmsted Creek no longer exists.
Water tracing with fluorescent dyes has confirmed that Olmsted Cave drains to Olmsted Spring. The rapid tracer responses at the springs indicate that flow is through dissolutional caves or conduits. Olmsted Spring is situated at the head of Lower Olmsted Creek. The spring and the creek are entirely contained with a park owned by the City of Hamilton, North of Highland Road. This park is zoned as “open space”. Much of it is grassed, and a paved footpath extends along its entire length. The original spring has been completely buried by fill adjacent to or beneath Highland Road. Currently, water emerges from the fill, as well as from a small culvert during high flow. The geomorphology of Olmsted Spring is entirely destroyed and restoration would be difficult or may even be impossible. Apparently, the burial of the spring under fill has not had a significant impact on its hydrology, since tracer tests indicate rapid groundwater velocities typical of karst. Lower Olmsted Creek extends from the spring for 150 metres before being directed into a storm sewer. Along its length, there are at least three discrete sinkpoints where the stream loses water. Much of the creek is forested, or undeveloped. There is some minor fill and garbage at the sinkpoints and along the creek. This has only had a minor impact on the geomorphology and hydrology of these karst features. Removing the garbage and fill would readily restore the sinkpoints, as well as the creek.
The surface karst features in this area have been slightly to severely impacted by existing urban development and ongoing construction. Nevertheless, some of the karst features that remain are key to the protection of the provincially significant karst systems within the ANSI (Area of Natural and Scientific Interest).
Here are some terms that may help you in your understanding of the above information, and in your answers. cave: A natural cavity in the ground which is large enough for human entry. An arbitrary minimum leng
dry valley: A valley which lacks a permanent surface stream.
karst: A landscape characterised by solution features such as karren, dolines, caves, sinking streams and springs.
karst window: A depression with a stream flowing across it, caused by collapse of bedrock into a cave passage. overflow sink: A sinkpoint for a creek that is only used under high flows when sinkpoints further upstream are unable to handle all the flow.
sinkhole: A sinkpoint.
spring: A natural outflow of water to the surface.
Congratulations to the CITO group for the shared FTF!