Ontario is known for its Precambrian bedrock covered by Cambrian, Ordovician, Silurian, Devonian, and Mesozoic aged rocks. Inside this bedrock is evidence of the ancient sea life that existed millions of years ago.
Devonian Age - 420 mya to 360 mya ( mya = million years ago)
- 85% of the earth was covered with oceans and the climate was warm
- Life exploded and modern fishes appeared in the oceans
- First forests and amphibians appeared on land
Silurian Age – 445 mya to 420 mya
- Seas levels are higher then today
- Shallow seas covered Ontario and the climate remained warm
- First land plants started growing near the coasts
- First land habitats appear, both near river and wetland
- Early fish and wingless insects appear
Ordovician Age – 485 mya to 445 mya
- Ontario was located near the equator and was periodically covered by shallow, tropical seas
- A 500,000 year long ice age contributed to an extinction of 85% of marine life and marked the end of the Ordovician age
Cambrian Age –540 mya to 485 mya
- First appearance of complex life represented by trilobites
- Sea levels rose steadily from 4m to 90 m
- Plants were simple one celled algae that often grew together in large colonies, making it look like one plant
Precambrian age – 460 mya to 540 mya
- Microfossils that resemble algae, cysts of flagellates, stromatolites
Rugose Corals
Rugosa are an extinct order of solitary and colonial corals that were plentiful during the middle Ordovician period. They are often referred to as horn corals because of a unique horn-shaped chamber with a wrinkled wall. Some solitary rugosans reached nearly a metre in length.
At the posted coordinates you will find a number of large Ontario sedimentary rocks that are chock full of rugose or horn corals. Look at the stone blocks on both sides of the path but particularly the one on the west side over the culvert.
Logging Requirements
To Log this Earthcache
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.
- What is the average diameter and length of the rugose corals found in this rock. Find examples similar to the photo on the cache page.
- Measure a 1 ft x 1 ft section on the rock and count the number of rugose corals you see. What is this number approximately?
Optional: Photos are appreciated and can include any other fossils you spot in the rocks at GZ.
