When that happens, no new rock is being formed and instead the rock is being worn away.This violent pushing upwards as two plates collided also caused the rock to become tilted.The observations in one location was extended to other locations by correlating the fossils.Small, rapidly evolving, common pelagic organisms make the best index fossils, but the original development was entirely pragmatic and empirical based on observations that fossil faunas occurred in a predictable, coherent fashion as show by Smith and his geologic map on England.This is because it contains striped layers which can be clearly seen.These striped layers are called a geologic (or stratigraphic) column.
It was a period of time when the collision of the earth's tectonic plates caused this part of the rock to be pushed upwards and exposed to the air---above the water level, just like the Grand Canyon is now.At the Grand Canyon a big part of the Paleozoic era can be seen, with a total of 11 individual layers---a mixture of sandstone, limestone and shale.Underneath the Paleozoic rocks should be Proterozoic (or Precambrian) rocks from 542 million or more years ago, since the Proterozoic era preceded the Paleozoic time period.(Walker and others, 2018) The geologic time column as we know it developed in the early 19th century.
An older scheme had used Primary (oldest), Secondary, Tertiary, and Quaternary (youngest), and the new scheme retained Tertiary and Quaternary but replaced the others.
A geologic column is a series of layers of different types of rock, placed by the settling of sediments over millions of years, often when the rock was a sea bed. At the Grand Canyon, the layers of rock stretch back an impressive 1.84 billion years.