Chap 2

Question 1

Define geology

Answer 1

its an earth science that studies the evolution of the earth , the materials of which it is made of and the processes acting upon them

Question 2

what are the 3 indirect methods to find clues from what we can see and what can be measured?

Answer 2

1. geophysics : studies earthquake
   2.geochemistry: composition of rock
   3.geochronology: methods to find the age of rocks

Question 3

what are the 2 geologic processes ?

Answer 3

1. internal processes : volcanic activity
2. external process: erosion , mass transfer

Question 4

what are the 4 eras

Answer 4

1. the Precambrian era
2. the paleozoic era
3. the mesozoic era
4. the cenozoic era

Question 5

what are the 4 main units of the geological time scale?

Answer 5

1. epoch
2. periods
   3.eras
   4.Eon

Question 6

what are the the 2 techniques for knowing the age of rocks?

Answer 6

1. Relative dating :
   - whats on top of old rocks
   -fossils inside the rocks
2. Absolute age dating:
   -carbon 14 technique
   -potassium argon technique

Question 7

how did the uplifting of the arabo affected eth

Answer 7

when the arabo eth landmass was pushed up in blocks as one mass, the tectonic force fractured the crust , and from those fractures came out huge quantity of lava. that outpouring formed the Ethiopian plateau surface and the floor of the present day rift valley

Question 8

how did the rift valley got formed

Answer 8

occurring at the end of the Tertiary period The East African Rift is one of the great tectonic features of Africa, caused by fracturing of the Earth’s crust.

Question 9

whats the extent of the rift valley

Answer 9

it extends from palestine-jordan in the north to Malwai Mozambique in the south , a distance of 7,200 kms

Question 10

what are the structural effects of the formation of the rift valley

Answer 10

• it divides the ethiopian plateau into 2
  -it seperates the arabian landmass from african landmass
  -it causes the formation of the dead sea , red sea and the gulf of aden troughs
  -it creates basins and fault depressions on which the rift valley lakes are formed

Question 11

what kind of life existed in each era?

Answer 11

invertebrates in paleozoic
reptiles in mesozoic
mammals in cenozoic
before life appeared in precambrian

Question 12

what characteristics make each era different

Answer 12

1. the relative position of land and sea
   2.the kind of climate
   3.the kind of animal and plant life that developed and excisted during that era

Question 13

how long was the Precambrian era?

Answer 13

from 4.5 billion years to 600 million years ago

Question 14

how long was the paleozoic era?

Answer 14

from 600 million to 250 million years ago

Question 15

how long was the mesozoic era

Answer 15

from 250 million years to 70 million years ago

Question 16

how long was the Cenozoic era?

Answer 16

from 70 million years to the recent time