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Detailed map of Mount Rainier's summit and northeast slope showing upper perimeter of Osceola collapse amphitheater (hachured line) The Osceola Mudflow, also known as the Osceola Lahar, was a debris flow and lahar in the U.S. state of Washington that descended from the summit and northeast slope of Mount Rainier, a volcano in the Cascade Range during a period of eruptions about 5,600 years ago.
The later Cornish term was quoit – an English-language word for an object with a hole through the middle preserving the original Cornish language term of tolmen – the name of another dolmen-like monument is in fact Mên-an-Tol 'stone with hole' (Standard Written Form: Men An Toll.) [6] In Irish Gaelic, dolmens are called Irish: dolmain. [7]
The point where a muddy material begins to flow depends on its grain size, the water content, and the slope of the topography. Fine grained material like mud or sand can be mobilized by shallower flows than a coarse sediment or a debris flow. Higher water content (higher precipitation/overland flow) also increases the potential to initiate a ...
Debris flows tend to move in a series of pulses, or discrete surges, wherein each pulse or surge has a distinctive head, body and tail. A debris flow in Ladakh, triggered by storms in 2010. It has poor sorting and levees. Steep source catchment is visible in background. Debris-flow deposits are readily recognizable in the field.
Debitage refitting is a process whereby the collected assemblages of debitage are painstakingly put back together, like pieces in a puzzle. This can sometimes indicate the nature of the tools being produced, although missing pieces are a significant problem.
Blanks are the starting point of a lithic reduction process, and during prehistoric times were often transported or traded for later refinement at another location. Blanks might be stones or cobbles, just as natural processes have left them, or might be quarried pieces, or flakes that are debitage from making another piece. Whatever their ...
Most of the fossil debris in chalk consists of the microscopic plates, which are called coccoliths, of microscopic green algae known as coccolithophores. In addition to the coccoliths, the fossil debris includes a variable, but minor, percentage of the fragments of foraminifera, ostracods and mollusks. The coccolithophores lived in the upper ...
The object at left is a prehistoric menhir recovered by du Châtellier. The slab was discovered in 1900 by Paul du Châtellier in a prehistoric burial ground in Finistère, western Brittany. [2] [5] It formed the wall of a cist burial. The cist measured 3.86 metres (12.7 ft) long, 2.1 metres (6.9 ft) wide and 1.86 metres (6.1 ft) high and was ...