The Bellot Strait separates the Boothia Peninsula, part of mainland North America, from Somerset Island to the north. Zenith Point on Murchison Promontory, on the southern side of the strait, is the northernmost mainland point of North America; it is 64 km (40 mi) farther north than Point Barrow, Alaska.
The Bellot Strait was discovered by the Canadian explorer William Kennedy and the French naval officer Joseph René Bellot, who reached it by dogsled in 1852. Until then, it was not known whether Somerset Island, to its north, was part of the North American mainland or a separate island. Although the Bellot Strait is now considered part of the famed Northwest Passage, Roald Amundsen did not pass through it on his first transit of the Passage in 1903-1906, but instead went around Somerset Island to its north and west. Today, Bellot Strait is still subject to ice that can linger into August, hampering navigation. However, with climate change and modern expedition-adventure cruise ships, the Strait is becoming more accessible and tourism traffic is rapidly increasing.
Although one might expect an extreme point of a continent to involve a dramatic fault or tectonic plate, the Bellot Strait in fact lies far inside the Laurentian (Canadian) Shield, nowhere near the edge of the North American Plate. There is currently no known fault in the strait to explain its formation, although several unspecified faults have been identified in the area (see the figure). Given the remote location, there is certainly a possibility that there is an as yet undiscovered fault in the strait.
Similarly, the roles that ice and water have played in the formation of the strait are likely major, but not well-defined. Glaciation and sea ice have obviously scraped the rocks clean, but whether this could be a glacial fjord that has cut through to form a strait is not known. Finding examples of lateral continuity in the rock patterns across the strait, north to south, could be illuminating. On our transit, we looked for such continuity but did not see anything obvious. Interestingly, although of uncertain significance, there is a similar, parallel waterway not far south. This waterway, Kangirlukutaak Inlet, comes within 1 kilometer of cutting through the peninsula and instead being the strait defining the northern edge of the mainland.
From: Geological map of the Arctic: Geological Survey of Canada Map 2159A. The Bellot Strait is marked in yellow. The thin black lines are unclassified faults. The pinkish rocks are unclassified; Metamorphic: undivided, Archean-Paleoproterozoic in age.
The walls of Bellot Strait are composed of Archean-Paleoproterozoic metamorphic rocks, dating from 4 to 1.6 Billion years ago. These are among some of the oldest rocks on earth; the Laurentian Shield was once the home of mountains far higher than any on earth today. Over this vast stretch of time, though, they have been eroded and scoured, largely by glaciation, until they have become the low-lying hills, nearly devoid of soil, that you see now. The patterns on the rock walls of Bellot Strait clearly show the effects of the high temperatures and pressures which created and shaped this metamorphic rock so very long ago, and the harsh climate will continue its work on the rocks and landforms in the future.
As a side note, the mineral garnet is commonly found in metamorphic and to a lesser extent, igneous rocks. Canada is a garnet-producing country, and on our passage, our geologist identified some garnets at the Fort Ross location. If you do find garnets in the area, post a picture!
LOGGING REQUIREMENTS:
Note that the coordinates for this EarthCache are in the Bellot Strait due north of Zenith Point. It is not necessary to get to that exact point, since ice conditions can be problematic, but you must have been at least to one of the ends of the Bellot Strait and observed enough to answer the following questions. Your visit must also be after the publication date of this cache; retrologging will not be permitted.
- Post a photo of yourself, your GPS, or your geocaching name written on a piece of paper. The photo must include one of the recognizable man-made structures along the Bellot Strait. Please see the attached pictures for examples; this can be Fort Ross at the eastern end, the cairn on Zenith Point, or the navigation marker on the small island at the western end. Alternatively, you may post a screenshot or photo of your GPS, clearly showing your position somewhere within the Bellot Strait; if you choose this option, please also name the ship you were on.
- Estimate how high the rock walls on the north and south walls of the strait are. Do these heights always match from one side of the strait to the other?
- Can you see visible evidence of ongoing shaping by ice?
- Describe the ice conditions during your visit, both in the strait and in the strait entrances at either end. (E.g., during my visit there was very little ice in the strait itself, with easy sailing through it, but almost immediately on exiting to the west entrance, we encountered extensive first-year sea ice.)
- What angle(s) to the horizontal do any visible layers in the walls form? Are all the angles along the strait similar, or are there considerable variations?
And…
- For extra extra extra credit—can you spot any areas of obvious lateral continuity in the rock layers from one side of the strait to the other—that is, where the layers match across the strait? If you do, please take pictures and tag the location.