Christmas Cove is an almost circular bay about 200m in diameter. The cove has significant geological formations from glacier activity, the only known evidence of Permian glaciation, ~270 Mya, in South Australia. The cove is also significant in the history of South Australia being chartered by Matthew Flinders during his 1802 visit.
Christmas Cove is a bedrock depression formed by ice movement and glacial scouring during the Permian. The cove preserves many glacier erosion features including striated bedrock surfaces, erratics boulder transported from another location, a rôche moutonnée asymmetric bluff and evidence of glacial clays and sediments. All your glacial geology christmas presents in one small bay.
The listed coordinates are a group of residual granite erratics weathered out of Permian glacigene sediments. It is reported that these rocks are similar to Encounter Bay granite about 60km to the east. Look for the odd one out.
At the nearby reference waypoint evidence of glacier scoring can be found on the rock surfaces at the base of the asymmetric bluff. Asymmetric erosional forms as a result of abrasion on the upstream side and plucking on the downstream side. The glacial scoring is evidence of ice movement.
Please visit the two earthcache sites, the listed coordinates and the nearby waypoint. Study the rocks and report your answers for the following tasks. Send your answers to the cache owner.
- Describe the erratic rocks at the listed coordinates. How many rocks? Crystal size? Colour? Texture?
- Describe the rock surface at the waypoint coordinates. Do you see any scores or striations? What direction are the major scores?