Historical Geology Understanding Our Planet\'s Past
carbonized plant material is commonly found between easily separated sedi- ment layers (Fig. 111). Animals were also buried in t ...
The amount of economically recoverable coal is upward of 1 trillion tons.The United States holds substantial reserves of coal (F ...
or the oxygen level in the bottom water must be low so the material does not oxidize before burial under thick sedimentary layer ...
tens of millions to a few hundred million years are required to process organic material into oil, mainly depending on the tempe ...
over, salt deposits in the Arctic regions indicate an ancient desert climate. Either the climate in the past altered dramaticall ...
comprising a sequence of late Paleozoic tillites and coal beds, extended over an area of several thousand square miles and reach ...
however. The relatively low extinction rates were probably due to a limited number of extinction-prone species following the lat ...
The continental collisions crumpled the crust and pushed up huge masses of rocks into several mountain belts throughout many par ...
Quebec and stretched all the way to Arkansas.The rivers reached their maxi- mum in the early Carboniferous, during times of low ...
long canine teeth projecting from their mouths. Mammal-like reptiles called dicynodonts also had two caninelike tusks and fed on ...
tion of mostly terrestrial animals some 30 million years after most of Pangaea was assembled. Pangaea remained intact for anothe ...
T his chapter examines the evolution of the reptiles during the Permian period and covers the greatest mass extinction in Earth ...
THE REPTILIAN ERA The reptile age, which had its beginning in the Permian and lasted 200 mil- lion years, witnessed the evolutio ...
amphibians.The superiority of the reptiles was largely due to their more effi- cient mode of locomotion. Even at an early age, 2 ...
reared up on their hind legs.Although most reptiles walked or ran on all fours, by the late Permian, some smaller reptiles often ...
codonts, which also gave rise to the crocodiles and dinosaurs.They thrived in the late Triassic, evolving quite rapidly, but app ...
marine reptiles. However, only the smallest turtles survived the extinction at the end of the Cretaceous. Turtles are the closes ...
lacked holes in the sides of their skulls, were once regarded as outsiders among modern reptiles because living reptiles and bir ...
sought out a shaded area or exposed itself to the wind. This appendage might have been a crude forerunner of the temperature con ...
Free ebooks ==> http://www.Ebook777.com THE APPALACHIAN OROGENY Perhaps the most impressive landforms on Earth are mountain r ...
«
4
5
6
7
8
9
10
11
12
13
»
Free download pdf