gl1 iii ki 3
Download
Skip this Video
Download Presentation
GL1 III KI 3

Loading in 2 Seconds...

play fullscreen
1 / 36

GL1 III KI 3 - PowerPoint PPT Presentation


  • 147 Views
  • Uploaded on

GL1 III KI 3. *The recognition on geological problem maps and description of: (i) Horizontal beds, dipping beds, strike and dip. Folds and faults as products of tectonic stresses Folds : limb, hinge, axis, anticline, syncline, axial plane trace, symmetrical and asymmetrical folds.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' GL1 III KI 3' - austin-chaney


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
gl1 iii ki 3
GL1 III KI 3
  • *The recognition on geological problem maps and description of:
  • (i) Horizontal beds, dipping beds, strike and dip.
  • Folds and faults as products of tectonic stresses
  • Folds: limb, hinge, axis, anticline, syncline, axial plane trace, symmetrical and asymmetrical folds.
  • Faults: (i) dip-slip: normal, reverse, thrust; throw – amount, relative movement of footwall/hanging wall (ii) strike-slip: transcurrent.
  • Fault displacement (=net slip).
  • (ii) Unconformities as hiatuses in the geological record. The formation of unconformities by Earth movements and sea level changes. The use of unconformities in dating Earth movements
  • Unconformities with or without angular discordance
  • (iii) Intrusive and extrusive bodies (dyke, sill, pluton, lava flow); metamorphic aureoles; mineral veins; superficial deposits (alluvial, glacial).
main terms
Main terms
  • *The recognition on geological problem maps and description of:
  • (i) Horizontal beds, dipping beds, strike and dip.
  • Folds and faults as products of tectonic stresses
  • Folds: limb, hinge, axis, anticline, syncline, axial plane trace, symmetrical and asymmetrical folds.
  • Faults: (i) dip-slip: normal, reverse, thrust; throw – amount, relative movement of footwall/hanging wall (ii) strike-slip: transcurrent. Fault displacement (=net slip).
  • (ii) Unconformities as hiatuses in the geological record. The formation of unconformities by Earth movements and sea level changes. The use of unconformities in dating Earth movements
  • Unconformitieswith or without angular discordance
  • (iii) Intrusive and extrusive bodies (dyke, sill, pluton, lava flow); metamorphic aureoles; mineral veins; superficial deposits (alluvial, glacial).
a bed of rock
a BED of rock
  • A layer
  • Stratum
  • Plural – strata
  • Top and bottom defined by bedding planes
  • Usually represents a minor gap in deposition, allowing the sediment to settle
law of original horizontality
Law of original horizontality
  • All beds deposited horizontally to start with
superposition
Superposition
  • Oldest beds on the base, younger on the top
  • Which is why way up structures are so useful – so we can work out which way up the rocks are
law of superposition oldest rocks at the base
Law of SUPERPOSITION (oldest rocks at the base)

younger

older

Trevor Quarry, Llangollen

way up criteria
WAY-UP CRITERIA
  • Small features on bedding planes which tell us where the surface was
rain imprints
RAIN IMPRINTS

Rain falling onto soft sediment may leave a small CRATER

Show sediment was pliable,

dry and it rained!

graded bedding
GRADED BEDDING
  • Heavier fragments fall fastest
  • In deep marine environments, turbidity currents bring unsorted material in, this settles out, largest particles first
mud cracks
MUD CRACKS
  • Drying out of mud
  • Curls up at edges
  • Polygonal pattern
load casts sole stuctures mud volcanoes flame structures
LOAD CASTS / SOLE STUCTURES / mud volcanoes / flame structures
  • Sandy layer of sediment deposited over a muddy layer of sediment
  • Sand is more dense and pushes downwards into the mud layer
  • Mud layer “erupts” through
washouts
WASHOUTS
  • Older bed eroded as river washes out sediment
cross bedding dune bedding
Cross bedding/dune bedding
  • Formation of a sand dune …..
  • http://www.youtube.com/watch?v=yRRl3HyR3mc (NB: note animal adaptions to living in such climates)
  • http://www.youtube.com/watch?v=iMCY9WMnzaw&feature=channel (Namibian desert)
ripples
Ripples
  • Symmetrical – bi-directional current – tidal area, waves
  • Asymmetrical – uni-directional current – river
  • http://www.youtube.com/watch?v=KYvWwbEi0A0&feature=related
  • http://www.youtube.com/watch?v=-sS-h_EjCwg&feature=related
  • http://www.youtube.com/watch?v=bVSH1q-2vhI&feature=related
pillow lava

http://www.youtube.com/watch?v=DdIUuUY0L9c

PILLOW LAVA
  • Underwater eruption
  • Pillow shapes – rapid solidification in contact with cold water
  • Convex upper surface
  • Sag on lower surface
revision
Revision:
  • Use GeoScience:
  • Page 191 – superposition
  • Page 192 – way up structures
  • Page 193 – included fragments
included fragments1
INCLUDED FRAGMENTS
  • PEBBLES – are fragments from an OLDER bed of rock which has been eroded
  • Conglomerate
  • Breccia
bgs map of kirby stephen

BGS map of Kirby Stephen

How do you know that the beds are horizontal?

bgs map of kirby stephen1

BGS map of Kirby Stephen

Bedding is parallel to the contours

How do you know that the beds are horizontal?

rocks originally deposited horizontally can get deformed
Rocks ORIGINALLY DEPOSITED HORIZONTALLY can get DEFORMED
  • Tilting (FROM THE HORIZONTAL) we call DIPPING
  • And the wavy patterns we call FOLDING
  • Push the edges of the page in front of you together …. You’ll notice it buckles up into wavy patterns
slide26

Geologists MEASURE the dip of the rock from the horizontal = the ANGLE OF DIPand we also record which direction that points = DIP DIRECTION

dip strike and apparent dip
Dip, strike and apparent dip.
  • The strike is a horizontal line drawn on a bedding plane.
    • Can be measured by using a compass to give a direction.
  • The Dip is the maximum amount that the bed is inclined from the horizontal.
    • It can be measured by using a clinometer to measure the angle and a compass to give the direction.
marker bed
MARKER BED
  • We tend to use a MARKER BED to see where the layer is
wenlock edge bgs map shows gently dipping rocks
Wenlock Edge BGS map shows gently dipping rocks.

Which way are the rocks dipping?

Ordovician

Silurian

diagram of an escarpment
diagram of an escarpment

Dip slope

Scarp slope

More resistant rock

Less resistant rock

Escarpments have a dip of 5-10o

escarpments are formed by gently dipping rocks the angle of dip is usually 5 o 10 o
Escarpments are formed by gently dipping rocks. The angle of dip is usually 5o – 10o.

Limestone dips away from the viewer

Eglwyseg limestone escarpment, Llangollen, N. Wales

vertical beds exposed on coast
Vertical beds exposed on coast.

Three Chimneys, Marloes Bay, Dyfed

natural arch produced by tough limestones which are near vertical
Natural arch produced by tough limestones which are near vertical.

Durdle Door, Dorset

Postcard from BGS

remind yourself
Remind yourself …..
  • What have you learned so far today?
ad