Yellow Chalk

Chalk

Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed under the sea by the accumulation and lithification of hard parts of organisms, mostly microscopic plankton, which had settled to the sea floor. Chalk is common throughout Western Europe, where deposits underlie parts of France, and steep cliffs are often seen where they meet the sea in places such as the Dover cliffs on the Kent coast of the English Channel.

Yellow

Yellow is a color between green and orange on the spectrum of light. It is evoked by light with a dominant wavelength of roughly 575–585 nm. It is a primary color in subtractive color systems, used in painting or color printing. In the RGB color model, used to create colors on television and computer screens, yellow is a secondary color made by combining red and green at equal intensity. Carotenoids give the characteristic yellow color to autumn leaves, corn, canaries, daffodils, and lemons, as well as egg yolks, buttercups, and bananas. They absorb light energy and protect plants from photo damage in some cases. Sunlight has a slight yellowish hue when the Sun is near the horizon, due to atmospheric scattering of shorter wavelengths.

yellow

Noun

1. The color of sunflower petals and lemons; the color obtained by mixing green and red light, or by subtracting blue from white light; the color evoked by light of wavelength around 580 nm; one of the three primary colors in subtractive color systems.
2. The middle light in a set of three traffic lights, the lighting of which indicates that drivers should stop short of the intersection if it is safe to do so.

Adjective

1. Of a yellow hue.
2. Lacking courage.

chalk

Noun

1. A soft, white, powdery limestone (calcium carbonate, CaCO3).
2. A piece of chalk, or nowadays processed compressed gypsum (calcium sulfate, CaSO4), that is used for drawing and for writing on a blackboard (chalkboard).

Verb

1. To apply chalk to anything, such as the tip of a billiard cue.
2. To record something, as on a blackboard, using chalk.