Coal the heat and pressure of deep burial causes the loss of water, methane and carbon dioxide and an increase in the proportion of carbon. Thus first lignite (also called "brown coal"), then sub-bituminous coal, bituminous coal, and lastly anthracite (also called "hard coal" or "black coal") may be formed. The wide, shallow seas of the Carboniferous Period provided ideal conditions for coal formation, although coal is known from most geological periods. The exception is the coal gap in the Permian–Triassic extinction event, where coal is rare. Coal is known from Precambrian strata, which predate land plants—this coal is presumed to
Brown Bear, Brown Bear, What Do You See? Brown Bear, Brown Bear, What Do You See? Brown Bear, Brown Bear, What Do You See? is a children's picture book published in 1967. Written and illustrated by Bill Martin, Jr. and Eric Carle, the book is designed to help toddlers associate colors and meanings to objects. The book itself has little to no plot. Instead, the narrator asks various animals what they see with the response usually being another animal, the respondent is then asked what they themselves see, and the process is repeated. It features a Brown Bear, Red Bird, Yellow Duck, Blue Horse, Green Frog, Purple Cat,