- do a second pass and add missing content from this paper
- Numerous natural erosional and depositional processes operate upon shorelines to create a diversity of coastal landforms. Waves are among the most important causes of this diversity as they remove, build, and shape beaches and sea cliffs.
- Jasper (Wikipedia)
Jasper, an aggregate of microgranular quartz and/or cryptocrystalline chalcedony and other mineral phases, is an opaque, impure variety of silica, usually red, yellow, brown or green in color; and rarely blue. The common red color is due to iron(III) inclusions. Jasper breaks with a smooth surface and is used for ornamentation or as a gemstone. It can be highly polished and is used for items such as vases, seals, and snuff boxes. The specific gravity of jasper is typically 2.5 to 2.9. Jaspillite is a banded-iron-formation rock that often has distinctive bands of jasper.
- The northeasterly growth of Semiahmoo Spit indicates that sediment eroded from Birch Point has been transported by littoral drift northward, leading to the growth of the spit.
- Of particular interest to artists and researchers are unusual weathering forms displayed upon the rocks within the shore zone. Mustoe (1971) studied the shoreline weathering characteristics of the Chuckanut Formation in order to explain some of the curious patterns that resemble cavities (Fig. 18). Mustoe refers to these features as aveoli and attributes their formation to biochemical weathering of the rock surfaces.
- However, it is clear that the sediment eroded from the cliffs is transported northward around the eastern and western flanks of the island where it is deposited in the form of two “horn-like” features, Brant Point on the east and The Portage on the west.
- The curvilinear shape of Birch Bay’s shoreline resembles similar shorelines around the world that are shaped by the refraction or bending of waves to the lee of a nearby headland
- The shoreline to the west of Nooksack delta has narrow beaches rimmed with low bluffs composed of glacial material.
- Semiahmoo Spit is a low depositional feature rising approximately two meters above mean high water. Its low undulating sandy surface is covered with beach and grass scattered trees.
- Semiahmoo Spit is essentially an appendage of Birch Point, which is a large headland lying between Drayton Harbor to the north and Birch Bay to the south.
- Bellingham Bay is a south facing semicircular shaped bay with approximately 20 km. of shoreline
- The Nooksack River enters the [Bellingham] bay from the north dividing the bay’s shoreline into two distinctive east and west sections.
- Northwesterly waves travel down Georgia Strait and are refracted around Birch Point into Birch Bay. Waves sweep counter-clockwise around Birch Bay transporting beach sediment in the same direction.
- Whatcom County’s southern most shoreline south from the Port of Bellingham for a distance of approximately 8 km. is composed of the Chuckanut Formation.
- At the northern most reach of Whatcom County’s shoreline is a spit approximately 2000 meters long trending northeasterly from the north side of Birch Point (fig.2.). The spit separates Drayton Harbor from Semiahmoo Bay and provides some protection for small boats and shoreline developments within the bay.
- The headland reaches maximum elevations of approximately 80 meters on the northeastern side near Drayton Harbor. From that point, the topography gently lowers westerly and southwesterly to the 25 and 30 meter high sea cliffs that rim the headland.
- It [Semiahmoo Spit] is only thirty to forty meters wide along its southern connection with Birch Point. High storm waves frequently overtop this area limiting access to the spit. Toward the northeastern end, the spit gently broadens to nearly three hundred meters, and appears to be quite stable.
- The shoreline to the east of the [Nooksack River] delta has been significantly modified over the past decades by landfills, piers, and breakwaters for numerous port oriented industrial and commercial establishments associated with the port and City of Bellingham.
- Sternberg (1967) has estimated the river to deposit 690,000 cubic meters of sediment into Bellingham Bay annually.
- Sandy Point is a south trending spit approximately 2500 meters long.
- Sandy Point is about three to four meters above mean sea level. Its low undulating sandy surface has been significantly modified by channel dredging and home construction.
- Winds up to 30 knots from the south and southwest could generate waves up to 2 meters (6 feet) high. During the summer, these waves are lower, corresponding to a weakening of the prevailing southerly wind velocities. Westerly winds up to 20 knots may build waves up to 11/2 meters (5 feet) high to attack Birch Point’s western shore.
- Point Francis or Portage Island, on the southwest side of the bay, was studied by Vonheeder (1972). He found the south facing shoreline of the island to be eroding from southerly wave attack.
- The Nooksack River has flowed between Lummi Bay, north of the Lummi Peninsula, and Bellingham Bay in the recent past (Easterbrook, 1973). At the turn of the century, the course of the river changed so that the main flow went into Bellingham Bay where it remains today.
- Southerly winds and waves prevail within Bellingham Bay. During the winter, waves up to 1.2 meters (4.0 ft.) are often generated within the bay by southerly winds 30 to 40 knots in velocity. In the sunnner, prevailing southerly wave buildup is smaller as winds are weaker. Southerly and southeasterly waves strike with greatest intensity along the south facing shoreline of the Lummi Reservation. The waves, often armed with drift logs, rapidly erode the bluffs. Occassionally, northeasterly winds create waves up to 0.5 meters (1.5 ft.) that break along piers and wharves on the east side of the bay; however, these waves are largely insignificant.
- Easterbrook (1973) shows Birch Point to be composed primarily of Bellingham glaciomarine drift with a veneer of sand and gravel. This material, when wet, has low strength and is prone to slumping or flow, particularly along the sea cliffs.
- Archeological evidence indicated the spit has developed across Drayton Harbor over the last 4000 to 5000 years (Grabert & Schwartz, 1972).