Blue goo is a sticky, plasticky, blueish-grey,

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

-textured soil derived from a highly weathered

serpentinite Serpentinite is a rock composed predominantly of one or more serpentine group minerals, the name originating from the similarity of the texture of the rock to that of the skin of a snake. Serpentinite has been called ''serpentine'' or ''se ...

mélange In geology, a mélange is a large-scale breccia, a mappable body of rock characterized by a lack of continuous bedding and the inclusion of fragments of rock of all sizes, contained in a fine-grained deformed matrix. The mélange typically cons ...

. The name derives from the soil's color; a result of undergoing

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: * Anaerobic adhesive, a bonding a ...

conditions and becoming gleyed. A greyer variation is called "grey goo". Blue goo is primarily found along the Northern California coast.

Parent material

The

Franciscan Complex The Franciscan Complex or Franciscan Assemblage is a geologic term for a late Mesozoic terrane of heterogeneous rocks found throughout the California Coast Ranges, and particularly on the San Francisco Peninsula. It was named by geologist Andrew ...

is the bedrock from which blue goo is derived. It stretches along the coastline from

Central California Central California is generally thought of as the middle third of the state, north of Southern California, which includes Los Angeles, and south of Northern California, which includes San Francisco. It includes the northern portion of the S ...

up to Southern

Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T ...

and contains sheared materials from both the

Pacific 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 contine ...

and

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacif ...

s that have accumulated in the

accretionary wedge An accretionary wedge or accretionary prism forms from sediments accreted onto the non- subducting tectonic plate at a convergent plate boundary. Most of the material in the accretionary wedge consists of marine sediments scraped off from the d ...

. The rock types that produce blue goo include: greenstones,

chert Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a ...

basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...

s, shales,

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 ...

schist Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes ...

s, and serpenitites. These materials mixed together forming a "plum pudding" or a mélange. This mélange decomposed through

weathering Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement) ...

to form blue goo.

Common features

Clay soils like blue goo have the highest water-holding capacity when compared with other soils, giving them a low draining capacity. This kind of habitat is unsuitable for most plants, but the Northern California coastline maintains high levels of vegetation year round. Due to blue goo's clayey texture, it slips when overly saturated. This slippage is increased in heavy rainfall areas and in shallow soils; deep soils have more total

pore space Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure ...

and are not as prone to slippage. These features contribute to the landslide-ridden environments found along the Northern Californian coast.

Locations

The Franciscan Complex, from which blue goo is derived, extends from Central California up the coast through parts of Southern Oregon. But blue goo has only been found in two Northern Californian regions located in Humboldt County: the

Trinidad Trinidad is the larger and more populous of the two major islands of Trinidad and Tobago. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is often referred to as the southernmos ...

region and the Orick region. Blue goo is thought to also be found in the Eel River region and along the Southern Oregon coastline.

References

{{Reflist Clay Geology of California