This guide begins at the main parking area at Black Point
The main trail at Black point is named for Malcolm Grant. He was a former Assistant Director of DEM and was very active in promoting public access.
If you are starting at the main parking lot, continue the trail guide below. If you are starting at the smaller south parking lot, go to Trail Guide B.
Just a few feet from the beginning of the Malcolm Grant (MG) trail is a trail to the left. This side trail makes a loop through a wooded area with larger trees which should make it good for birding during spring migration. This trail returns to the MG trail in about 150 yards.Continuing on the MG trail, you will notice a couple of places where bedrock is exposed.
Further on there is a 4-way intersection. The loop trail comes in from the left and the MG trail turns to the right. There is a somewhat difficult but manageable descent straight ahead. At the bottom, more bedrock is exposed ahead and in both directions.
The bedrock in the area of Black Point is the Narragansett Pier/Westerly Granite which is Permian in age (275 million years old).
The granite formed in a magma chamber that was 15-20 km below the surface. The minerals in the granite include potassium feldspar, white plagioclase, smoky quartz, garnet, muscovite, biotite and magnetite.
Just to the left is a large boulder. This is a glacial erratic and it is different from the bedrock in the area. That’s because it was brought here by glaciers. During the Late Wisconsin glaciation, which culminated 26,000 years ago, glaciers advanced from the north to the south and picked up, transported and deposited glacial material in Rhode Island. Large boulders, called erratics, can be found in the Black Point area (see Figure 1& 2 below)
Figure 1 Glacial Erratic
Figure 2 Same Erratic Closer Up
Back on the MG trail, about 100 yards down the trail is a path to the left. This leads to a nice observation spot overlooking the ocean. This is a good place to check for wintering waterfowl, such as loons, scoters, harlequin and eider ducks and mergansers. Last winter there was a king eider, shown below, which is not too common in this area.
Figure 3 King Eider
Further down the trail, at the bottom of the hill, are a couple of little paths. The first, on the left, goes to a rocky beach and the second, straight ahead, goes onto a larger area of exposed Narragansett Pier/Westerly Granite bedrock. You can see a variety of textures (grain sizes) in the minerals. The texture was controlled by the volatile content in the magma. Water-rich magmas have rapid crystal growth and large crystals whereas drier magmas have fine-grain crystallization. You can come up with a chronological sequence by looking at the textures. In some areas of Black Point medium-grained granite is cut by a younger coarse-grained pegmatite (see Figure 4 below)
Figure 4 (Photo by Crystal Gryszkiewicz)
These cracks in the rocks (see Figure 5) that are either joints (a fracture where there is no relative displacement of the rocks on either side) or faults (where there is relative displacement along the fracture). The joints are due to unroofing. When the material above the magma chamber (the the Rhode Island Formation) was removed, the rock expanded and cracked.
Figure 5 (Photo by Jacob Schlapfer)
Back on the trail, at a little bend in the trail is a little path and just back to the left of the path is another glacial erratic (Figure 6).
Figure 6
It’s not visible from the path, but this erratic has been split in two, as can be seen in Figure 7. Water in a crack freezing in the winter or salt from the salt water crystallizing can create pressure that will eventually crack the rock.
Figure 7
Further along the trail is a cross put there in memory of Erica Lee Knowles. Erica was a 23-year-old URI student who was killed in a drunk driver accident. The cross has an interesting story in that it disappeared and was found on a beach in Orient Point in Long Island, NY. The story is described in this link. https://turnto10.com/news/local/family-gets-missing-memorial-cross-back-call-it-a-christmas-miracle
Figure 8
If you step off the trail near the Erica Lee Knowles cross and look back at the bank, you will see a dirt bank which is being eroded by high waves. You will also see rounded rocks on the bank face. These rocks have been buried here for about 20,000 years. This chaotic mixture of soil, sand, gravel and rocks is called till. The distinguishing characteristic of till is that the material is unsorted. The sorting process is done by water and is ongoing. If you look behind you towards the water you will see rocks, gravel and sand. In storms, the waves come in and erode the bank. The fine grained clay and silt are washed away leaving the rocks, gravel and sand. This bank is part of the Pt. Judith Moraine, mentioned above, which extends down to the Pt. Judith Lighthouse.
Also from this point you can see Quahog Rock jutting out into the ocean, and can be seen in the top right corner of Figure 8 and also in Figure 9. This also more of the Narragansett Pier/Westerly Granite formation.
Figure 9
Just a few yards further along the trail is another trail on the right. This is the Quahog Rock trail which leads back to the south parking lot.
Continuing on the MG trail, after a few hundred yards, you will see the ruins of Windswept, an Oceanfront estate built in 1895. The ruins that you see ahead are of the carriage house. Nothing remains of the 21 room, 5 bedroom mansion which stood in an open area on the right, where you can see some stone walls and stone posts. A trail from the mansion site leads north, splits, and both splits end up at Quahog Rock Trail. More information on Windswept is available at this website: https://www.sandhillcovephoto.com/page/windswept/#/page/windswept/
Figure 10
On the left is the mile long Scarborough State Beach. Seaweed tends to wash up in the corner and this section is known as Stinky Beach. The seaweed is a popular feeding spot for migrating shorebirds in the spring or late summer.
Figure 11. Stinky Beach
Just before the carriage house ruins is a trail to the right which will lead back to the south parking lot. Also there is a narrow trail just past the carriage house which will also connect to the trail back to the south parking lot. It will be necessary to walk along Ocean Rd. to get to the main parking lot.
Hope you enjoyed your walk. Thanks to O. Don Hermes and Beth Laliberte, URI Geosciences Department for help with the geology information.