Scotia Bluffs form a 2-mile (3-kilometer) series of gray

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

cliff In geography and geology, a cliff is an area of rock which has a general angle defined by the vertical, or nearly vertical. Cliffs are formed by the processes of weathering and erosion, with the effect of gravity. Cliffs are common on co ...

s along the north bank of the Eel River near

Rio Dell, California Rio Dell (Spanish: ''Río Dell'', meaning "Dell River") is a city in Humboldt County, California, United States. It is located on the west bank of the Eel River north of Scotia at an elevation of 161 feet (49 m). The population was 3,363 at t ...

Geology

The course of the lower Eel River changes from northeasterly to westerly as it encounters the resistant Rio Dell Formation of

fossiliferous A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

upper

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

. River turbulence has created deep pools beneath steep sandstone cliffs on the northeasterly bank. Tributary streams, including Nanning Creek, cut steep, narrow canyons through the cliffs. The southwesterly bank of the river is an

alluvial plain An alluvial plain is a largely flat landform created by the deposition of sediment over a long period of time by one or more rivers coming from highland regions, from which alluvial soil forms. A floodplain is part of the process, being the sma ...

extending to the

estuary An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

. The community of Rio Dell occupies the bank opposite the cliffs. The cliffs expose abundant remains of ancient

clams Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two shel ...

and

sand dollar Sand dollars (also known as a sea cookie or snapper biscuit in New Zealand, or pansy shell in South Africa) are species of flat, burrowing sea urchins belonging to the order Clypeasteroida. Some species within the order, not quite as flat, are ...

History

Pacific Lumber Company The Pacific Lumber Company, officially abbreviated PALCO, and also commonly known as PL, was one of California's major logging and sawmill operations, located 28 miles (45 km) south of Eureka and 244 miles (393 km) north of San Francisc ...

built a railroad across the face of the cliffs between 1883 and 1885 to transport lumber to

Eureka, California Eureka (Wiyot: ''Jaroujiji'', Hupa: ''do'-wi-lotl-ding'', Karuk: ''uuth'') is the principal city and county seat of Humboldt County in the Redwood Empire region of California. The city is located on U.S. Route 101 on the shores of Humboldt ...

. This alignment was followed by the

Northwestern Pacific Railroad The Northwestern Pacific Railroad is a regional shortline railroad utilizing a stretch of the 271 mile mainline between Schellville and Windsor with freight and Sonoma–Marin Area Rail Transit (SMART) commuter trains. Formerly, it was a regi ...

to avoid bridging the lower Eel River. The rail line maintained an elaborate series of benches, retaining walls, and trestles approximately above the river during low summer flows, and the cliffs extend above the track. These trestles and benches have been frequently damaged by floods and by massive blocks of sandstone falling from the upper cliffs. Rail service was interrupted in 1907, 1913, 1933, 1938, 1942, 1946, 1955, 1956, 1957, 1964 and 1971. A railroad bridge crew was assigned to work exclusively on the Scotia Bluff trestles from 1916 through 1959. Flood waters reached track level in 1955 and were over the railway in 1964. Three trainmen were killed when engine 184 was swept into the river by a 17 January 1953 landslide off the bluffs.

References

External links

* {{Eel River History of Humboldt County, California Landforms of Humboldt County, California Rock formations of California