Granite 1 Cave
Length: 53m | Grade: 5D | Surveyed: 1996-09-22
| Field | Detail |
|---|---|
| Surveys | Survey (gif), Survey (pdf) (3.3 Meg) |
| Dimensions | Passage Length: 35 m; Box: Length 35 m, Width 5 m, Height 14 m |
| Rock | Granite |
Description
The cave is a 35 m long crack in the granite base that underlies most of the Peninsula. The entrance is 7 m above sea level and 5 m above the floor of the crack. This drops into the entrance chamber. 10 m from the entrance is the base of a boulder choke, which leads up to a second chamber. The floor of the second chamber is mostly large blocks of rubble that have fallen from the ceiling and walls. The solid floor of the chamber lies approximately 3 m below the top of the rubble floor.
The wall of the western end of the upper chamber is made up of large, shattered blocks. On the southern edge of the wall, very narrow cracks lead to the west, and the sound of the sea can be heard through the cracks. On the northern edge of the wall, a narrow, broken passage leads up to a small chamber. From this terminal chamber, a narrow vertical crack leads towards the west. At the time of the survey, a strong south-easterly wind was blowing, which resulted in a strong breeze blowing into the entrance of the cave, and down these cracks. This indicates that there is an exit for the wind somewhere.
Minerals
On the ceiling of the entrance chamber are small clusters of what appeared to be gypsum crystals. The longest was approximately 8 mm long. These crystals were also found on the ceiling of the sloping passage to the upper chamber, and in the upper chamber. A creamy/white clay-like substance, which may be kaolin, covers many of the boulders and parts of the walls of the upper chamber.
The southern wall of the terminal chamber is a shattered block, while the northern wall is solid granite, which is showing signs of exfoliation. Thin sheets of the granite are peeling off, to reveal the rusty red/brown colours of iron oxide.
Biota
There were a number of cormorant skeletons in the entrance chamber, and what appeared to be the shoulder blade of a small seal. There was bat excrement on the floor of the entrance chamber, and of the rubble chamber, but no bats were found. There were also a number of spiders and other small invertebrates in the cave.
Survey
Survey — Granite 1 Cave — click image to open PDF