Spectacular cliffs of Silurian red quartzfeldspar porphyry form the backdrop for Rattling Brook, which falls over 50 m before passing under the highway bridge. To see the falls, drive 4 km north of the Post Office in Kings Point on the paved road along the shore that leads to the community of Rattling Brook. There are picnic areas both below the bridge on the beach, and above the bridge where a short trail leads through trees and over a jumble of mossy talus blocks almost to the base of the falls.
The resistant intrusive rock that forms the cliffs is also seen in the stream bed just above the bridge. Much of the cliff face is covered with grey lichen, but where clean rock is exposed, the porphyry shows its dark orange-red colour. It contains abundant white and pink crystals of quartz and feldspar up to 5 mm in size. This cliff is part of a major fault zone, along which the rocks west of Green Bay moved north compared with those to the east. The straight, high coastline of Green Bay has formed along the line of the fault.
These rocks were deposited in a riverbed, and strong river currents have created crossbedding in the sandstone sections. The various attitudes of the crossbeds show that the current direction changed frequently as the river shifted its channel. The entire sequence was later cut by narrow, white quartz veins.
Note the sand, gravel and rounded boulders above and below you on the hill, and the boulders in South Brook and West Brook when you cross them. These were deposited on the delta between 12,000 and 14,000 years ago by a much larger river than those seen today. The river flowed across a land surface still depressed by the weight of the melting glaciers (see Glacier panel).
On the west side of the cove is a high cliff of red Silurian volcanic breccia. Large angular blocks of red lava up to 4 m across are contained in a finer red matrix of volcanic ash; the whole was deposited onshore by an exploding volcano, similar to Vesuvius in Italy, or Mount Saint Helens in the northwest USA. For a closer look at the deposit walk part way around the shore (easiest at low tide).
Warning! Beware of falling rocks from the overhanging cliff. There are plenty of large blocks along the shore to give you a closer look at the material in the cliff.
Pillow basalt is exposed on the west side of Route 380, 8.2 km north of the TCH junction. The road passes a pond on the east side, then curves and climbs a hill, with an exposure of pillow lava part way up.
The pillows vary from 15 to 100 cm across. They are cut by later diabase dykes which have the same composition as the basalt, but lack the bulbous form, and break off as angular pieces. Warning! Beware of falling rocks from the low cliff.
At the northern end of the exposure, you can scramble up the steep slope to the top, and see that the weathered rock has a lot of small holes in it. These were formed when gas bubbles were frozen in the rock as it cooled.
Warning! Do not go too close to the cliff edge.
Drive to Pilley's Island on Route 380, and watch on your left toward the far end of the town for Mine's Pond Road. Park by the entrance to the road (it is a short dead end). The yellow rock cut on the left at the intersection is felsic volcanic rock containing a network of pyrite veins. If you walk a short distance up the road, you can see timbers and some of the mining equipment from the "Old Mine" on your left. There are blocks of massive pyrite for collecting down on the levelled area. The outcrop face, right beside the old timbered area, is breccia, composed of blocks of lava and pyrite, and formed during an explosive volcanic eruption.
To see more of this type of volcanic rock, sulphides and an old prospect pit, drive approximately 700 m farther on Route 380, past Forestry Road, and turn left at Bight/Strickland's Road (taking Bight Road on the left). This is a rough gravel track for about 300 m. Drive or walk to where it ends above Bumblebee Bight, then continue walking along the shore of the Bight. This is best done at low tide.
The first point after the end of the road has massive blocks of pyrite in an extremely rusty face; the pyrite is in bulbous, pillow-like masses. Nearby, red jasper occurs in the material between the pillows.
About 750 m farther along the shore is the "Henderson Mine", a couple of old prospect pits on the shore with bright yellow waste piles in front. Between the pits are blocks of massive pyrite in breccia. Where the pyrite has been leached out by rain and weather, you can see remnant "boxwork" structures: a fine honeycomb of quartz plates that originally separated the pyrite grains.
Black, glossy hornblende crystals up to 10 cm long make up 90% of the rock. The white mineral is feldspar. The gabbro is intruded by dykes and veins of diorite and pink granite. Many of the veins incorporate angular fragments of the gabbro. The pistachio green alteration mineral that coats partings is epidote.
Newfoundland and Labrador Traveller's Guide to the Geology
Edited by: S. Colman-Sadd and S.A. Scott, 91 pp. + map, 1994