Granite 3 Cave
Length: 95m | Grade: 5D | Surveyed: 1996-09-22
| Field | Detail |
|---|---|
| Surveys | Survey (gif), Survey (pdf) (3.1 Meg) |
| Dimensions | Passage Length: 95 m; Box: Length 60 m, Width 33 m, Height 12 m |
| Rock | Granite |
Description
About 70 m further along the base of the cliff from Granite Cave 2 is the side entrance to Granite Cave 3. This low flat entrance leads to the upper end of a large entrance chamber. A joint can be seen in the ceiling of this entrance passage. To the north is a small broken chamber, the wall of which is formed by a large block that has fallen from the ceiling. The chamber slopes down towards the south to a large entrance, which opens out onto the sea.
The main passage of the cave leads off to the east for 30 m. This passage has fairly solid granite walls, and is undercut by 2 m on the southern side. The passage terminates in a chamber, the western wall of which is solid, while the eastern wall is formed by a rubble pile that has fallen from the ceiling.
Just off this chamber to the south is a low, narrow passage which leads to the pillar chamber.
Minerals
While the cave is formed entirely in granite, large boulders of other material are found in the cave. In the northern collapse chamber are boulders of a fine grained, crumbling, well stratified rock, which is tan in colour and breaks easily. This rock has a greasy, clay-like feel to it when wet, and is probably shale.
The ceiling of the southern undercut passage is solid granite, and has many small nodules on the ceiling. It appears that much of the cement material has been removed, leaving the larger particles in place.
The same white crystals found in the other granite caves occur on the ceiling of the main passage, and the collapse at the end of the passage is covered in what looks like kaolin.
The most interesting feature in this cave is found in the pillar chamber. In the centre of the chamber is a 0.6 m high, 20 cm diameter pillar of red clay-like material. The ceiling of this chamber is also covered in red clay, and has a black, shiny metallic finish. Hanging from the ceiling are red stalactites, some of which have broken off to reveal a structure of concentric layers. The longest stalactite formation is approximately 3 cm long.
Biota
A number of spiders were observed in the northern chamber, but little else in the way of life was seen. One small black spider with creamy yellow markings was collected. Small amounts of bat guano were found on the floor of the main passage, but no bats were seen.
Survey
Survey — Granite 3 Cave — click image to open PDF