The  Rock  Cycle  its  Story  

Forma4on  of  Rocks  in  More  Detail  

Do  Now:  •  Every  day  the  man-‐Mr.  Doughman,  bakes  the  cookies.    He  makes  the  dough,  puts  it  in  the  oven,  and  bakes  them.    Then  he  lets  them  cool  and  harden.    Another  man  –Mr.  Crumbles,  takes  the  cookies  and  crumbles  them,  building  up  layer  and  layer  of  cookies.  Then  Mr.  Squeezy  comes  along  and  takes  all  the  cookies  and  squeezes  them  together  over  and  over.    The  cookies  get  warm  again  in  his  hands  as  he  does  this.  The  sun  sets  and  rises,  and  Mr.  Doughman  makes  the  cookies  again,  over  and  over…  

Hey,  that’s  a  lot  of  cookies…  

•  Compare  the  gentlemen  in  the  story  to  the  Rock  types  we  learned  about:  – Mr.  Doughman  – Mr.  Crumbles  – Mr.  Squeezy  

– Something  that  occurs  over  and  over  again  is  ________________?  

See  p6  ESRT  

•  To  Read  the  Rock  Cycle,  follow  the  arrows  around  

 

Physical Setting/Earth Science Reference Tables — 2011 Edition 6

Ero

s ion

Wea

ther

ing

&E

rosi

on(U

plift

)

Metam

orphism

MeltingSo

lidific

atio

nMeltingW

eatherin

g &Ero

sion

(Uplift)

Metamorphism

Weathering & Erosion

(Uplift)

Heatand/or Pressure

Heatand /or

Pressure

Melting

Ceme

ntation

and Burial

Comp

action

and/or Deposition

IGNEOUSROCK

SEDIMENTS

MAGMA

METAMORPHICROCK

SEDIMENTARYROCK

0.0001

0.001

0.01

0.1

1.0

10.0

100.0

PAR

TIC

LE D

IAM

ETE

R (

cm)

Boulders

Cobbles

Pebbles

Sand

Silt

Clay

1000500

50100

105

10.5

0.10.05

0.01

STREAM VELOCITY (cm/s)

This generalized graph shows the water velocityneeded to maintain, but not start, movement. Variationsoccur due to differences in particle density and shape.

25.6

6.4

0.2

0.006

0.0004

Rock Cycle in Earth’s Crust

Scheme for Igneous Rock Identification

Relationship of TransportedParticle Size to Water Velocity

Pyroxene(green)

Amphibole(black)

Biotite(black)

Potassiumfeldspar

(pink to white)

(rel

ativ

e by

vol

ume)

MIN

ER

AL

CO

MP

OS

ITIO

N

Quartz(clear towhite)

CH

AR

AC

TER

ISTI

CS

MAFIC(rich in Fe, Mg)

HIGHER

DARKER

FELSIC(rich in Si, Al)

LOWER

LIGHTER

CRYSTALSIZE TEXTURE

Pumice

INT

RU

SIV

E(P

luto

nic)

EX

TR

US

IVE

(Vol

cani

c)

EN

VIR

ON

ME

NT

OF

FOR

MA

TIO

N

Plagioclase feldspar(white to gray)

Olivine(green)

COMPOSITION

DENSITY

COLOR

100%

75%

50%

25%

0%

100%

75%

50%

25%

0%

IGN

EO

US

RO

CK

S

non-

crys

talli

ne

GlassyBasaltic glassObsidian

(usually appears black)

less

than

1 m

m FineBasaltAndesiteRhyolite

1 m

mto

10

mm

CoarsePeri-dotiteGabbroDioriteGranite

Pegmatite

10 m

mor

larg

er Verycoarse

Scoria Vesicular(gas

pockets)

Dun

ite

Non-vesicular

Non-vesicular

Vesicular basaltVesicular rhyolite Vesicularandesite

Diabase

Start  with  Magma,  these  are  types  of  Igneous  Intrusions  which  will  become  

Igneous  Rock  

Some4mes  pieces  of  the  surrounding  rock  remain  unmelted  and  become  part  of  the  igneous  rock  (xenolith)  

Igneous  Intrusions-‐cut  through  the  parent  rock  

Making  Sediments  and  Sedimentary  Rock…  

•  UpliU  •  Weathering    •  Erosion  •  Deposi4on  •  Burial  •  Compac4on  •  And  Cementa4on  (natural  glue-‐  silica,  calcite  or  iron  oxides)  

Sediment  Sor4ng  in  Land  Derived  Sedimentary  Rocks  

Sor4ng  of  sediments  produces    separa4on  of  the  par4cle  sizes(p6)  

•  Pebbles/gravels  are  dropped  first  (form  conglomerate)  

•  Sands  (form  sandstone)  •  Silts,  clays  are  dropped  last  (form  shale)  

Chemical  Origin  in  Chemically  formed  Sedimentary  Rock  

•  Water  contains  dissolved  minerals,  which  can  fall  out  of  solu4on  (precipitate)  due  to  evapora4on  or  chemical  ac4on  

•  Limestone  can  be  formed  from  4ny  grains  of  calcite  deposited  from  sea  or  lake  waters  

•  Other  examples  are  rock  salt  (halite)  and  rock  gypsum  

Organic  Origin  

•  Calcite  is  dissolved  out  of  rocks  on  land,  carried  to  an  ocean  or  lake,  and  taken  out  of  the  water  by  shell-‐producing  organisms  (eg.  Clams,  oysters,  sea  snails)  

•  When  these  organisms  die,  their  shells  pile  up  and  are  broken  down  into  fragments,  and  can  form  organic  limestone  

Metamorphism…  

•  Metamorphic  rocks  are  not  formed  from  magma  or  sediment  

•  Metamorphic  rocks  “morph”  (change)  from  exis4ng  rock,  due  to  heat,  pressure  and  chemicals  

•  Pressure  squeezes  grains  closer  together  (more  dense,  less  porous)  

•  Heat  and  chemicals  may  rearrange  the  par4cles  (new  minerals  may  be  formed)  

Types  of  Metamorphism  

Regional  Metamorphism:    large  areas  of  rock  are  under  intense  heat/pressure,  which  occurs  during  mountain-‐building  

•  Heat  comes  from  fric4on  of  rocks,  and  pressure  from  overlying  weight  and  the  squeezing  of  moving  rocks  

Contact  Metamorphism:    when  hot  magma  forces  itself  into  overlying  rock  (intrusions)  and  bakes  the  rock  

Contact  Metamorphism  

Results  in  Fola4ons  if  more  then  one  mineral  makes  up  rock  

•  Occurs  when  the  pressure  on  the  rocks  squeezes  minerals  into  parallel  layers  

•  The  rocks  tend  to  split  easily  along  these  layers  

What  is  the  Rock  Cycle?  •  Is  the  repeated  series  of  events  by  which  rock  gradually  and  con4nually  changes  from  one  type  to  another  

•  Theses  events  are  geological  events-‐meaning  they  happen  in  the  Earth’s  crust  or  on  it  

•  Another  word  to  describe  this  is  geologic  process  

•  Can  you  name  some  of  these  processes?  

Reading  the  Rock  Cycle  Chart  

•  See  page  6-‐7  in  the  ESRT  

•  First  Classify  your  Rock  Samples-‐work  together  with  your  partner  

•  Place  them  on  the  Rock  Cycle  diagram  enlarged  copy-‐work  together  to  complete  Part  II  of  Lab  

Complete  Understanding  the  Rock  Cycle-‐for  homework  

1.    When  granite  changes  into  schist,  what  geologic  processes  does  it  have  to  undergo?          2.    Change  gneiss  into  conglomerate,  which  geologic  processes  are  involved?              3.  Which  type  of  rock  can  change  into  the  same  kind  of  rock  without  going  through  the  en4re  rock  cycle?      

Sum  Up:  

     •  What  are  3  great  “truths”  about  the  Rock  Cycle?    Think  about  everything  we  talked  about  today  and  see  if  you  can  list  them  below:  

       

Sum  Up:  (well  maybe  5  truths…)  1. The  Rock  Cycle  is  a  model  of  the  natural  changes  that  occur  in  rocks  and  rock  material  

2. Shows  all  Rocks  are  made  from  other  rocks  or  rock  remains  

3.   Shows  Rocks  are  classified  upon  basis  of  forma4on  

4. Shows  that  there  are  a  variety  of  ways  that  rocks  can  change  at  the  surface  or  within  the  Earth  

5.   It  keeps  on  going  and  going….and  has  been  since  the  Earth’s  Spheres  formed  

Follow  up  Assignment:      •  Complete  a  RAFT  to  help  you  understand  Rocks  and  the  Rock  Cycle  

beeer.    The  direc4ons  are  as  follows:      •  Role-‐You  are  a  Geologist  •  Audience-‐Students  in  a  High  School  Earth  Science  Class  •  Format-‐Can  choose  any  way  to  write  this-‐poem,  story,  email,  riddle,  

song,  etc…  •  Topic:    Earth’s  Dynamic(Ever  Changing)  Crust  and  the  Rock  Cycle      •  Be  prepared  to  share  your  RAFT  with  the  class  on  Tomorrow!  (read  

aloud)      

Food  for  thought…  

•  Do  we  have  any  influence  on  the  Rock  Cycle?  If  so,  what?  

•  What  force  is  driving  the  Rock  Cycle?