What is an Outlier?
The word "outlier" refers to a portion of stratified rock separated from a main formation by erosion. Many years ago a channel was cut through the escarpment in this location. On the east side of that channel is the Milton Outlier. Today part of the channel is known as the Nassagaweya Canyon where Limestone Creek flows.
The northern portion of the Milton Outlier drains into the Sixteen Mile Creek watershed. While the southern two-thirds of the Outlier drains into the Bronte Creek watershed. These creeks start as springs at the point where the Amabel Formation sits on the less pervious Clinton Formation bedrock.
As an elevated bedrock formation the Milton Outlier is isolated from the surrounding area. The water table of the Outlier is highest toward the centre and decreases toward its outer edges. The water table on the Outlier is sustained solely by precipitation. The groundwater in the Outlier moves downward and outward through the Amabel formation discharging where it hits the edges of the formation beneath it.
The Milton Outlier lies approximately 4 km (2.5 miles) long in a north south direction and 3 km wide (1.8 miles). It has an approximate area of 11 square kilometres (4.7 sq. mi.). The north, eastern and western edges of the Outlier form a steep Amabel dominant scarp whose lower edges are mantled by glacial drift. Below the Amabel limestone formation, the Queenston shale and the Whirlpool Sandstone which has been quarried along the northeastern slopes of the Outlier. The southern most edge terminates in a cliff promontory known as Rattlesnake Point. The Outlier is separated from the main Escarpment face by a narrow deep valley; the Nassagaweya Canyon. A glacial meltwater channel and a kame gravel terrace are located southwest of Rattlesnake Point.
The northeastern portion of the Milton Outlier drains into the Sixteen Mile Creek watershed. The Outlier is the headwaters of a number of first order permanent and intermittent streams. Many small streams emanate from the Escarpment face at Milton Heights. Numerous springs along the face are evidence of groundwater discharge providing a base flow for the tributary streams. These streams generally start as springs at the point where the Amabel Formation sits on the less pervious Clinton Formation bedrock.
As an elevated bedrock formation the Milton Outlier is isolated from the surrounding area. Because of its geological isolation, the water resources of the Outlier are very fragile. The primary source of surface and groundwater on the Outlier is from precipitation. The general pattern of groundwater movement is radial. Because the surface soils are generally low permeability clay till soils above the Queenston Shale bedrock, the water that emerges along the northeastern edge of the Outlier does not re- infiltrate as it does on the west edge of the Outlier where it is hemmed by permeable gravel and sand deposits.
To Log this EarthCache, send the answer the following questions (via my profile page) based on your observations, the signage at GZ, and the above readings.
Do not post your answers or signage photos in your log
1. Where did the name of this Valley originate, and how did it get it? What does Nassagaweya mean?
2. What were some of the Erosional forces that contributed to the formation of the Nassagaweya Canyon
3. How wide is the Nassagaweya Canyon? To do this, take a hike into the canyon, and up the other side onto the Rattlesnake Point Trail. Use your GPS to measure the distance to the posted coordinates from the trail. For consistence, ensure your measurement crosses through Waypoint 1 in the Nassagaweya Canyon.
4. What is an Outlier?
5. What makes the Nassagaweya Canyon an ideal location for the nesting of turkey vultures?
6. Measure the altitude at the posted coordinates, and the altitude again at Waypoint 1 (on the Canyon Trail) to determine the depth of the valley.
7. Photos are not necessary, but would be greatly appreciated.
Do not post your answers or signage photos in your log