Geological Maps

Question 1

what is an angular unconformity?

Answer 1

it is an unconformity where horizontally parallel strata of sedimentary rock are deposited on tilted and eroded layers, producing an angular discordance with the overlying horizontal layers (see diagrams online)

Question 2

how is an angular unconformity formed?

Answer 2

• beneath the sea sediments accumulate
• later tectonic plate movement causing uplighting and deformation of the sedimentary layers during mountain formation
• erosion strips away the top of the folding layers leaving an uneven plain with exposed folded layers
• new sediment is deposited on top of the layers
• where the surface of the new layers meet the folded layers is called the angular unconformity

Question 3

when you get a curve in the strata what is this called?

Answer 3

folding

Question 4

when the strata layers get thinner and thicker what is this called?

Answer 4

stretching

Question 5

what is a fold?

Answer 5

a bend or buckle in a pre-existing structure that has occurred due to deformation, this is often associated with tectonic movement and mountain building

Question 6

what is a plunging fold?

Answer 6

when the folded strata is at an angle to the ground plane

Question 7

what is a fault?

Answer 7

a fault is a fracture in the earths materials, often with opposing sides having been displaced (shows a displacement)

Question 8

what is the bedding plane?

Answer 8

the layer that separates sedimentary rock layers that are distinguishable from those above and below it