The sand collection of Dr. Richard Sternberg is on display in the lobby of the Ocean Sciences Building. Each quarter our sediment group plans to highlight and briefly discuss groups of interesting samples--so keep your eyes out for the “Sediment Stories Quarterly” posted on the collection. Below is the newly posted Summer quarter sediment story.
SEDIMENT STORIES, Summer 2024: Here and There
Context- This Sediment Story has no over-riding theme, or focused objective. Beach sediment samples are selected based on extreme geographical location (e.g. edges of continents, islands, oceans). These beaches are then briefly analyzed to see what they might tell us!
Background-Two methodologies commonly used to study beaches and coasts are: 1) Descriptive Sediment studies, e.g. grain composition, size, shape, spatial distribution (beginning with the Challenger Expedition 1872-1876); and in later years as physical data collection and chemical/biochemical analytical techniques developed, 2) Process Oriented studies, which evolved to focus on transport of sediment, (e.g. processes that build beaches and coasts). The first method describes "what is there", the second analyzes "how did it get there". These two distinctions still exist though modern methods have modified them substantially.
Beach location
- World’s northernmost city: Ny Alesund, 79° N, Svalbard Islands, Norway.
- Southernmost mainland of South America: Punta Arenas, Magellan Strait, Chile.
- Southernmost Africa: Cape of Good Hope (aka Cape of Storms), South Africa.
- Southernmost Iceland: Vik, Reynisdrangar Iceland.
- Southernmost Sweden: Smygehamn, (aka Southern Scandinavian Peninsula), Sweden.
Beach summary in terms of description of sediment characteristics, and dynamic physical and sedimentary processes (in italics)
- Beach face adjacent to the pier and covered with gravel and rounded coal particles; spillage from loading ships from nearby Russian mines and rounding/sorting due to moderate wave action.
- Diverse along-coast mixture of coarse sand and gravel; Pleistocene glacial moraine deposits sorted by subsequent strong winds, waves, and currents of recent times.
- A sandy pocket beach deposited between small headlands; quartz sandstone cliffs eroded by stormy/rough seas where Indian Ocean warm currents meet cold Antarctic currents.
- Black sand and gravel beaches and cliffs extending throughout Iceland. The Mid-Atlantic Ridge crosses Iceland where the North American and Eurasian tectonic plates meet; dynamic processes include e.g., volcanoes, glaciers, geothermal pools, waterfalls, rivers.
- Coarse sands and pebble sediment on this exposed southern peninsula; sorted by waves/currents focusing on this exposed coastal area.
Comments- Several interesting aspects of this Sediment Story are suggested:
- beach sediment characteristics describe any beach but their stories could be spatially unconnected from one another;
- physical and associated sediment transport processes build beaches and although more limited in their breadth, their stories are interconnected in time;
- physical and sedimentary processes occur in space and time so arguably, any mix of sediment types and sediment transport processes would have revealed a similar story as the extreme beaches selected for this story.
A general conclusion is that the range of physical and sediment transport forcings are active worldwide so, among other things, are revealed in the beaches they build and the characteristics of their deposited sediment (e.g. encompassed within this complete sand collection). Thus:
Sedimentologically speaking, we inhabit an amazingly dynamic, beautiful, and wonderous planet!
