Description and significance. Anaplasma marginale is the most prevalent tick-borne, livestock pathogen worldwide and poses a considerable constraint to animal health. The disease results in significant morbidity and mortality of United State's (US) cattle population, which affects the exportation of beef.
The Geological period consists of time periods in the origin and evolution of earth. The earth is about 4.5 billion years old. The time from the origin of the earth to the present is divided into super eons, eons, eras and periods. The Precambrian period is a super eon that is sub-divided into three eons: â¢ the Hadean Eon (4.5 to 3.8 billion years before present), â¢ the Archean Eon (3.8 to 2.5 billion years before present),, and.
(b). Geologic Time. Geologists and geomorphologists describe the Earth's geologic history through a temporal system known as the geologic time scale (Table 10b-1). On this scale, time is measured using the following four units of time: eons, eras, periods and epochs.ulticellular organisms ruled the planet during the eon known as the Phanerozoic. Table 10b-1 describes some of the important geologic events that have occurred since the Earth's formation some 4.6 billion years ago. Table 10b-1: Geologic time scale.