Please follow the road into Presqu'ile Provincial Park and take the turn off for Owen Point. Coordinates will take you to the general parking area and signs are posted for the trail.
All stages of this earthcache can be found along the Owen Point Trail in Presqu’ile Provincial Park. Please be respectful of signs posted.
The Owen Point Trail begins at the Owen Point Trail parking lot and meanders through the natural beach area. The trail is approximately 1.5 km long and will take 30 - 40 minutes to complete. It can be seasonally wet in places. Viewing pods provide access for bird-watching along the shoreline. Dogs are not permitted on the trail or in the beach area at any time.
Geocache Description:
Presqu'ile in French and means “almost an island”. It’s origin goes back 450 million years to the middle Ordovician period. At that time a warm, shallow sea covered this part of North America. At the bottom of this sea, limey sediment and shell fragments from the sea's inhabitants slowly accumulated. Southern Ontario was covered by this sea for almost 150 million years and by the time the water was gone 300 million years ago, the sediments at the bottom of the sea had been squeezed and turned into a package of sedimentary rock at least five kilometres thick. Many of the sea creature's shells had been transformed into fossils in this rock.
In the millions of years since the sea disappeared, this package of rocks has been eroding away. For the last two million years, the time of tropical seas had long passed and this part of North America had been subjected to a series of ice ages, with kilometre-thick ice sheets scouring the land and further eroding away the rocks. When the last ice sheet melted about 12,000 years ago, it left behind vast quantities of sand, gravel, and boulders that it had scoured from the land beneath it. It also left behind a lot of water which filled the low areas of the land forming the proto-Great Lakes, much like the Great Lakes we see today but even bigger. These lakes are often referred to as 'glacial lakes'.
The glacial lake at Presqu'ile has been called Glacial Lake Iroquois and its former shoreline is now marked by a long, gentle escarpment or, in other places, a low ridge of old beach deposits that parallels today's Lake Ontario shoreline.
Definitions:
Tombolo: a deposition landform in which an island is attached to the mainland by a narrow piece of land such as a spit or bar.
Spit: a deposition bar or beach landform off coasts or lake shores. It develops in places where re-entrance occurs, such as at a cove's headlands, by the process of longshore drift by longshore currents. They develop where there is a sudden change in the shape of the coastline such as at a headland. Normally, longshore drift transports beach sediment along a coastline.
Bar: is formed as a spit grows across a bay, joining up two headlands.
Lagoon: the area of water dammed by the bar will eventually be filled by deposition
It is just in the last 10,000 years that the elements have formed the Presqu'ile we know today. Presqu'ile Provincial Park includes the Presqu'ile Peninsula as well as Gull and High Bluff Islands.
The mainland portion of the park is a feature known as a tombolo, a peninsula formed as the result of sand deposition between the mainland and a former island.
The Presqu'ile tombolo is a fascinating formation, unequaled in size, complexity, and degree of development on the Great Lakes. Three of the five islands that rose above the surface of the lake, High Bluff, Gull Island and Sebastopol Islands, are still separated from the mainland.
The two islands have attached to the mainland to form the tombolo.
One small former island now forms the area around Owen Point. The much larger former Presqu'ile Island now makes up most of the southern part of the Presqu'ile Peninsula.
The Presqu'ile tombolo formed as waves coming from the west and southwest brought sand and gravel, which glaciers had deposited in the Lake Ontario basin, closer inshore. The sand and gravel were then deposited in the shallow waters of Presqu'ile Bay. As the deposits deepened, sand spits formed on the mainland and on the former Presqu'ile Island. Early sand spits from the mainland formed “The Fingers”. A great spot to view The Fingers is from the viewing station just north of the Camp Office. N 43 59.659
W 077 43.152
Eventually a northern spit grew across the intervening channel and became joined to the much smaller island spit. Once the two spits had joined creating the tombolo, sand and sediment, which had formerly moved eastward into Presqu'ile Bay became trapped to the west of the tombolo and a beach began to grow westward.
The process of sand deposition continues today, at a remarkably rapid rate. Air photos suggest that the beach deposits grew an average of more than two metres a year between 1949 and 1986.
Today the tombolo remains a dynamic formation subject to the whims of the wind and waves. It is most noticeable at Owen Point. It grows and shrinks continually and since 2006 Gull Island has been attached twice to the Point only to be broken apart again. Only time will tell what the water may give or take away.
Logging Requirements:
Please send me your answers within 4 days of posting your found log. If there is more than one cacher in your party, include the names in your group. Only one person needs to send me the group answers. No Spoiler photos please. Found logs posted without proof you visited the site will be deleted.
Questions:
-
After stopping at the Park Gate, on your way to Owen Point parking area , what proof is there that this is a tombolo. Use geological descriptions.
-
Between 1949 and 1986, beach deposits grew an average of _________ metres a year? Do you think this will continue and why or why not?
-
When standing on the dunes at Lookout 5 on the Owen’s Point trail take a projection to Gull Island stating the bearing and distance.
-
a). Between which Lookouts can you see a Lagoon?
b) How many Lagoons are there along Owen Point Trail?
5. Do you believe that future sand and gravel deposits could eventually link Gull and High Bluff
islands
6. Alternative question to substitute for one of the above. When at the Viewing Station, north of
Camp office at posted co ordinates .. what is the geological land formation called in front of you.
Reference:
Peterson, N.N. (1969). Carbonate Petrology, Structure and Stratigraphy of the Middle Ordovician Carbonate Rocks in the vicinity of Kingston, Ontario. Unpublished Ph.D. Thesis, Queen's University, Kingston.
https://www.friendsofpresquile.on.ca/geology-and-formation-of-presquile.php