Canoe Rock.
The canoe rock is a rock that, as the name suggests, strongly resembles a canoe. Hollowed out with protruding edges and a distinct point at one side one does not need much fantasy to see the boat shape. It is a bit narrow to sit in for larger adults, but children will enjoy pretending to row their boat.
Visit the rock, admire its shape and that of the heavily eroded rocks around it, and don't forget to enjoy the view from the site.
Geology of the area.
The area is geologically rather diverse, with minor outcrops of various rock formations in the area. The landscape around the canoe rock is rather distinct in that there are boulder fields and tors (rocks standing on the top of a hill) here. The canoe rock is part of one such tor, the other rocks also show very interesting erosion patterns. Shapes like this canoe are of course purely accidental, and a result of differential erosion of the rock.
The lithology of the rocks is lapilli ash crystal tuff, rich in conspicuous plagioclase and in places containing lithic clasts of pale grey sandstone and dark grey mudstone. Occasional lithic clasts of porphyritic volcanic rock up to 150 mm occur and some of these are welded. The top of these lapilli ash tuffs does not crop out in these areas, and the basal contact of the main outcrop is faulted along most of its length. (source)
These lapilli ash crystal tuffs come in basically two variants: welded and not welded. If the ash and larger clasts were not cooled down sufficiently when they reached the ground, they would weld together, and become very rigid and erosion resistant. The non-welded variety, as is found here, is eroded easily.
Tors and boulder fields form when the rocks around them are eroded away, leaving the harder parts exposed. Such landscapes are very typical for easily eroded rock, such as these lapilli ash crystal tuffs, or the in Hong Kong very common granite.
Logging tasks.
To log this cache, please provide answers to the following questions and send them to CO.
- Lapilli ash crystal tuffs somewhat resemble conglomerates. Both contain larger clasts contained in a finer grained matrix. Conglomerates are typically formed in localities such as stream beds of rivers or at the bottom of oceans out of pebbles and sand, while these tuffs are formed by course volcanic ash and lapilli-sized clasts raining down from the sky following a volcanic eruption. Look carefully at the texture of the rock the canoe rock is made of. What clues does this texture give you that this is not a sedimentary rock, formed in water?
- Lapilly ash crystal tuffs are easily eroded. How is it then possible that these rocks are standing out in the open, exposed to rain and sun?
- How do you think the canoe rock got its shape?
Getting there.
The rock is up the hill, it can be reached easily following existing paths. The paths are steep at time, but overall easy going. The terrain is very exposed with only grasses and other low vegetation. In summer bring plenty of water and wear a wide-rimmed hat.
From Ma On Shan take village bus NR84 or taxi to the end of Ma On Shan Tsuen Road, and walk up from there along Ma On Shan Country Trail. At the pavilion and intersection with the MacLehose Trail, waypoint "Junction", turn right, continuing up, until you reach the rock.
From Sai Kung take minibus 3A to Po Lo Che, walk up along Ma On Shan Country Trail and MacLehose Trail until the pavilion at waypoint "Junction" where you turn left and uphill to the rock.