Another difference between oil and acrylic paints is the versatility offered by acrylic paints-acrylic is very useful in mixed media, allowing use of pastel ( oil & chalk ), charcoal, pen, etc.

Nothing is actually required-beyond suitable comfortable and flexible clothing-and it is not uncommon to see people bouldering with just climbing shoes, a chalk bag, and a crash mat.

Alternatively, liquid chalk is sometimes used.

The history of computing is longer than the history of computing hardware and modern computing technology and includes the history of methods intended for pen and paper or for chalk and slate, with or without the aid of tables.

The Cretaceous (, ), derived from the Latin " creta " ( chalk ), usually abbreviated K for its German translation Kreide ( chalk ), is a geologic period and system from circa to million years ( Ma ) ago.

The Cretaceous was named for the extensive chalk deposits of this age in Europe, but in many parts of the world, the Cretaceous system consists for a major part of marine limestone, a rock type that is formed under warm, shallow marine circumstances.

The Cretaceous is justly famous for its chalk ; indeed, more chalk formed in the Cretaceous than in any other period in the Phanerozoic.

* Calcium sulfate ( CaSO < sub > 4 </ sub >· 2H < sub > 2 </ sub > O ) is used as common blackboard chalk, as well as, in its hemihydrate form better known as Plaster of Paris.

Solutional caves are the most frequently occurring caves and such caves form in rock that is soluble, such as limestone, but can also form in other rocks, including chalk, dolomite, marble, salt, and gypsum.

Blending is most easily done with a medium that does not immediately fix itself, such as graphite, chalk, or charcoal, although freshly applied ink can be smudged, wet or dry, for some effects.

Pencil, from Old French pincel, a small paintbrush, from Latin a " little tail " ( see penis — pincellus is Latin from the post-classical period ) is an artist's fine brush of camel hair, also used for writing before modern lead or chalk pencils ; the meaning of " graphite writing implement " apparently evolved late in the 16th century.

Often a chalk or gypsum component is present.

These chalk beds were deposited at the bottom of what was once the Western Interior Seaway, a large shallow sea over what now is the midsection of the North American continent.

Dating and understanding the various phases of activity is complicated by disturbance of the natural chalk by periglacial effects and animal burrowing, poor quality early excavation records, and a lack of accurate, scientifically verified dates.

Moorland and chalk downland is easily damaged by regular use, and takes many years to recover.

It is common to find chert or flint nodules embedded in chalk.

Chalk has greater resistance to weathering and slumping than the clays with which it is usually associated, thus forming tall steep cliffs where chalk ridges meet the sea.

Because chalk is porous it can hold a large volume of ground water, providing a natural reservoir that releases water slowly through dry seasons.

The bedrock is chalk which is covered with clay.

The bedrock is permeable chalk and the water table lies permanently below the level of the riverbed, allowing water to drain out of the river through swallow holes in the bed and banks.

At Leatherhead the river leaves the chalk bedrock, moving on to London Clay.

Geological map of south-east England, with areas that have chalk bedrock shown in light-green.

In its western section, the national park extends north beyond the chalk escarpment of the South Downs into a quite different and strongly contrasting physiographic region, the western Weald, taking in the valley of the western River Rother, incised into Lower Greensand bedrock, and the densely wooded hills and valleys of the Greensand Ridge and Weald Clay south of Haslemere.

It was a credit to the strength of Bargate that it was chosen for the main structure, standing on top of the natural chalk bedrock, which would have been more readily available.

To form the stacks, the sea gradually eroded along the joints and bedding planes where the softer chalk meets harder bedrock of the rock formations to create a cave.

It rises in Priory Gardens in Orpington in the London Borough of Bromley, where rainwater permeates the chalk bedrock and forms a pond at the boundary between the chalk and impermeable clay.

The enclosure is formed by a ring of pits dug into the chalk bedrock, with ' causeways ' between the pits.

The area contains a wide variety of habitats based on the chalk bedrock, which hosts a wide range of flora and fauna, including some nationally rare species.

Spending much of his youth on Bear Island, in Penobscot Bay off the coast of Maine, he had trouble with geometry, being unable to understand the abstraction necessary to imagine that a chalk dot on the blackboard represented a mathematical point, or that an imperfectly drawn line with an arrow on the end was meant to stretch off to infinity.

The geology of the area, like much of South Wiltshire and Hampshire, is largely chalk.

The higher areas consist of a sedimentary layer of gravelly soils, known as the Blackheath Beds, that spread through much of the south-east over a chalk outcrop — with sands, loam and seams of clay at the lower levels by the river.

* A chalk carving very much like the Uffington White Horse is featured extensively in A Hat Full of Sky by Terry Pratchett, and the author discusses the Uffington White Horse specifically in an afterword.

East of Dorchester the river runs over sands, clays and gravels which overlie the chalk ; as the valley gradient is gentle the Frome has deposited much sediment here and thus created a broad flood plain.

The water table rises at this point and much of the water which drained out of the channel through the chalk returns through springs in the riverbed.

As the Cretaceous chalk layer in southern England is typically tilted, chalk downland formations often have a marked scarp slope on one side, which is very steep, and a dip slope on the other, which is much shallower.

* Austin chalk formation, which underlies much of central Texas

Snodland shows much evidence of industrialisation, particularly chalk extraction.

But ChalkZone went much farther, positing a world where everything that had ever been drawn in chalk by anyone came to life in the alternative chalk universe, endowed with the soul and personality its creator had intended for it.

The South Downs National Park forms a much larger area than the chalk range of the South Downs and includes large parts of the Weald.

The South Downs are formed from a thick band of chalk which was deposited during the Cretaceous Period around sixty million years ago within a shallow sea which extended across much of northwest Europe.

Behind this is a band of weaker, easily eroded rocks, and behind this is a stronger and much thicker band of chalk, which forms the Purbeck Hills.

Two miles away is the Westbury White Horse, a famous chalk figure on the side of Westbury Hill first recorded in the 18th century, which is visible from Westbury and much of western Wiltshire, although not from Edington.

Today, much of the commercially produced paper is acid-free, but this is largely the result of a shift from china clay to ( cheaper ) chalk as the main filler material in the pulp: chalk reacts with acids, and therefore requires the pulp to be chemically neutral or alkaline.

He suggested various other practical issues which supported his ideas including that open cast chalk extraction would require moving the material further than necessary and that shallower chalk deposits have much of their minor mineral content leached out by groundwater.

The ground contains much limestone and chalk, which makes the flora rich.

Sittingbourne and its consumed suburb of Milton today is a growing town, with much recent expansion by way of house-building in the former chalk and brick clay works digs.

The Ridgeway in fact probably ran from The Wash along the chalk escarpment across Britain via Avebury to the English Channel across Salisbury Plain, a much longer route than the current national footpath suggests.