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2 n d
Edition
... t o .
~
I
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This book is meant for educational and learning purposes. The aulhor{ s} of the book has/have taken all reasonable care
to ensure that
the
contents of the book do not violate any existing copy
righ
t or other intellectual p
ro
perty
ri
ghts of any
person in any manner whatsoe
v
er: In the eve
nt
the authoi(
s}
has/have been unable
1 0
lrae
k
any source and i
f
any copyright
has been inadvertently infringed. p l ease not
i
fy the
publi
sher in writing for corrective ac
ti
on,
Printed
a
t Baba
B ar
kha Nath Printers
37, MIE,
Bahadurgarh,
Haryana t2
4
507
Typeset by Sri Krishna Graphics
B-22
, Sou
th Ganesh
Nagar,
Delhi
110 092
Pu b li
shed by Rajiv
B
eni
for
Macmi l lan Publ i she
rs
India Ltd.
2110
,
Ansari Road,
Daryaganj ,
Ne w
D e l
hi
110 002
ISBN
I0: 0230-
63870
-8
ISBN
13:
978.0230-63870-9
Com
panies and
representativ
es throughout the world
MACMILLA
N PUBLISHERS INDIA LTD.
D e l
hi
Bang
alore Chennai
Kolkata
Mu m b a i
Ahmedabad Bhopa l Cha nd
i
garh Coimbatore
Cut tac
k
Guwaha t i Hubl i Hyderabad Ja ipur Lucknow Madura i
Nagpur
Patn
a Pune
Th
i ruvananthapuram
V is a
khapatnam
First published, 1993
Reprin
ted, 1 9 9 7
2
007
eight times)
Se
c
ond edition, 1 2 009
.
All r ights
reserved
.
No part
of th i
s publicat ion may
b e
reproduced or
transmitted,
in
any
fo
rm or
b
y any
mea ns
,
without
permis s io
n
.
Any
person
who does any
unauth
o rized act in re lation to th i
s
publicat ion
m
ay be l iable to criminal
prosecu
t ion and
c ivi l cl
aims for
damages
.
C
N Chenna Kes avulu, 1993
,
2 0 0 9
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5
.4 Sequence
of
Formation of Diff
e
r
ent
G
r
oups
of
Rocks
5 . 5
Ro
c
k
Cycle
5.
6 Civil
E
ngin
ee
ring
I
mportance
of
Petrology
5 .
2
Definit ion
of a R oc
k
5 3
Cl
as s ification of R
oc
k
s
5
I
S
h
ell Stn1c n1re of rhe Earth
5
. PETROl.oGY
4.
4
Impo
rt an
t
D
e
t
ails
of
C
ommon
R
o
c
k-fo
rmin
g
M
i
nerals
4.3 Brief S k
et
ch of Common R ock-
fo
rming M in erals
4
.
2
S
pe
c ial Fea tu res of S
il i
cate
M
in erals
4
. 1 Type
s
of
Roc k
-f
orming M i
ne
rals
4. COMMON
R
OCK
-
FORMJNG
M INERA
LS
3 .
7
D i
a gn
o
s
tic or
D is
tin gu i
s
hing
P
h y s ical
P
roperties
3 .6
Sig
n ifican
c
e of D ifferent P h ysica l
Prope
rt ies in M ineral
3.5
D
ifferent M ethods of
S
tu d
y
of M
in
eral
s
3
.4 C o m m o
n
R oc
k
-f
orming M i
ne
rals
an
d Their A
b
u n
d
anc
e
3
3
Mode
of
Foan
a t
i
o
n
o
f
M
in
era l
s
3
.
2
Defini t
io n
of a Crystal
3
1 Defiojt
oo of a Min
era
3.
M
IN E R A L O GY
2.3
R iv
e
r
a
s a G
eo l
ogi
c
al A g
e
nt
2.2 Weathering of R
o
c
ks
2 . 1 G
e
olog i
c
al
Agents
2 GEN E
R
Al.GFOlOGY
1 .
3
Sc o
pe
of
G
e
ology
1 .2 I m portance of
G
eology
in
Civil Engineering
Vil
IX
1
2
5
7
11
1
2
1 4
2
7
39
39
41
4
3
44
4
5
I
d
entif i
c
a
tion
48
(j()
61
61 I
6
1
65
6 8
94
94
95
96
1
00
IO I
1 02
I.
M ain and Allie
d Bra n
ches of
G
eology
Pre
ce
t
o th e
Sec
ond
Ed
ition
Prece o th e F irst Edition
1.
GEOLOGY
CO
NTENTS
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256
1.9 G
ro
u
nd Water
P
otential
in D
iffe
re
nt Parts of India
253
254
I 1.7
Geo
l
ogical Controls on G round Water Mo veme
n
t
I I
.8 F
lu c tua tion of the Water Table Level in
U n
confined A qu ifers
248
250
1
1.5
Cla
s
sification of Rocks B ased on
Poros
ity and
P
e
rm
eability
1
1.6
W ater
T ab
le and
Ty
pes of
G
rou
nd
W ater
244
245
1 1
.3 D
istri
bu tion of
Rain
fall
1 1 .4 Porosity and
P
e rme a b ili ty
242
1 1 A d vantages of U s ing
G ro
u nd Water
24 1
I.
Source
s
of
G
r
ou nd Water Su pp
l
y
240ntroduction
240
I
.
GROUNDWATER
2360.3 Effects of Joints and Their C ivil
E n g i
neering Importance
232
0
.
2 Effects of
Fault in
g an
d
Their Civil
E n
gineering
Im
portance
228
0
. I Effects of Fo lding and Their Civil Engin
e
ering Im portance
227ntroduction
2270.
IMP
OR T A N
C
EOFGEO
LOGI
CAL
S
TRUCTURES
226
.6 Common Symbols to
Indicat
e S ome G
e
o l
o g
ical Structures
222
. 5
U nc onf o rm
ity
Causes for Deve lop me
n
t of Structures
190
171
175
176
190
8.2 C o m
m o
n Structures and
T ex
tures
of
M etamorph
ic R oc
ks
8.3 C lassification of M e tamorp
hic R
oc
k
s
8.4 Descr ip t ive Study of C o m m on M e t am o
rphi
c R
oc
ks
9.
SIRU
CTURALGEOLOGY
162
.
1
M e ta m
o
rphism
1 6 1
nt
roduc
ti
on
1
61
7
.4
D
escriptiv e Study of
Co m m o
n
S
e
d im
entary
R
ocks
8. METAMORPHICROCKS
150
135
145
7
.2
Cl
assification of Sedimentary
R
ocks
7.3 Common Structures and
T
extures of
Sedim
entary R ocks
134
.
1
Sedimentary Rocks on the Earth's Crust
1 34
ntr
od11ct
i
on
134
1 2 3
125
6
.6 Suitability of Igneous
R
ocks for Building an
d F
oundation
6.7 M egascopic De sc r i
p
tion of Relatively C o m m o
n
Igneo
u
s
R
oc
k Types
7. SEOIME
NTARYROCK
S
109
1 II
Ill
1 1 5
6.2 M iscellaneous
6.3 C o m m o
n
Igneo
u
s Rocks and R ela tio
n
of
T
heir
C
onstituent M inerals
6.4 Class ificatio n of
I
gneous
R oc
ks
6
5 Stn
c t11r
es an
d Texh1res
103
103
1 04
6. IGNEOUS ROCKS
Introduction
6
.
1 Form s of
I
gneous
R oc
k
s
xu
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c,opvnghted mater ia l
16 .2 Seismic Refraction M ethod
16 . 1 E le ct r i cal R es is tivity M et
h
od
Introdu
ct
i
on
15.3
Principles of E xp loration
G eoph y
sics
I 5.4 Classification of Geophysical Methods
15.5 Well-logging
1
6
.
GE
OPHYSICAi. I
NVE
STIGAT
IONS OF C
I
YII
.
EN
GINEE
RI
N
G IMPDR
TA
NCE
15. GEOPHY
S
I
C
AL
I
NV
EST
IG ATIONS
I n t roduc t
i
on
15.
I
B ranches
of
G e o p
h
ysics
15.2 Necessity of
Geoph
ysical
Inves t i
gations
14
. LANDS
LID
E
S
Introd
uction
14
. 1 I
m
po r t
ance of
L an
dslides
14.2 Class i f i c
a
tion of Earth M ovements
14.3 Causes of Landslides
1
44 Effects
of
Landslides
14.5 Preventive Measures for L a n d s lides
13.9 Determining the De
p
th of the Focus of an Earthquake
13.10 Effects of Earthquakes
13
.
1 1
Civil Engineering Considerations in Seismic Areas
13
.
1
2 Plate
Tec
tonics
an
d E ar t
h
q
u
ake D is
t
rib
u
tion
13.8 L oca
ting th
e
E
p
icentre of an E
a
rthq
uake
13.6 Intensity of Earthquakes
13 .7 M agnitude
o
f the Ear th qu akes
13 .5
E a
rt
h q
u
a
ke W aves
13.4 E a rthqu
a
k
e
s a nd
Fa
u lt ing
13.3 S
e
ismic
B
elts
a
nd Shield A r ea s
13.2 Class i f i ca
t
ions and
Ca
uses of E ar t
hq
u akes
1
3.
I
E a
rt
h
q
uake
Te
rm
in
o
l
o
gy
I
nt
rod
uction
1
3. E
AR
T
HQU
AKES
12 .6 Importance of the
Stu
dy of Stratigraphy from the Civ il Engineering
Poin t
o
f V iew
12.3
Geo
log i ca l T ime Scale
12
.4
G eo
l
og i ca
l
D iv
isions of
In d
ia
12 .2 Princ i
p
les of Stra t igrap
h
y
I
I.IO Ground W ater Ex
plo
ration
11.11 Effects of Excessive Tapping of G ro und W ater
11.12 Waterlogging
12. S T R A
TI
G RAPHY
I
ntroduction
12 .
I A
ims of Str
a
tigraphy
C on
te
n
ts
XIII
257
260
260
2 6 )
261
2 6
2
262
264
267
268
284
2 8
5
285
286
286
28
8
28
8
289
290
29 1
293
294
294
295
298
300
300
300
3
01
303
306
306
308
30
8
308
309
311
312
329
331
33
1
332
345
1
2 .
5 M ajor
S
t rat
i
graph
i
cal
U n
its
of
In d
i
a
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Copvnghted maienal
Index
443
ibliography
441
0.7 A Few E xa
mp
l
es of Tunne
l
s of Interest and Importance
428
429
4 2 9
430
4 3 0
440
2 0 . I Purposes of Tunnelling
20.2 Effects of Tunnelling on the Ground
20.3 Lining of Tunnels
20.4
Economical
Aspects of Tunnelling
20.5 Geological Considerations for Successful Tunnelling
20
.6
Overbr
eak
427
ntroduction
42
7
0. TUNNEL
S
425
9 .
7 L a n d s l ide Occurre;ices
4 2 5
9 .6 S e
i
s m
i
c Activity in R eservoir Areas
413
420
19 .4 Water-tightness and Influencing Factors
19 . 5 Reservoir Silting
4 1 2
9 .3 Effect of Evaporation
412
9 2 Capacity
of
t
h
e Reservoi
r
4 1 2
9 .
I Co ns
iderations for
Successf
ul Reservoirs
411
ntrodu
ctjoo
4JJ9, RESERVOIRS
398
8 ,7 Case Histories
3 8 4
3 9 6
18.5 Geological Considerations in the Selection of a Dam Site
18 .6 Stages of Investigation in the Selection of a Dam Site
383
8
.4 Purposes of Dams
3 8 0
381
18.2 A Dam and Its Parts
1 8.3 TYPes of Dams and Beari
n
g of Geology of Site in Their Se lection
3 7 7
8
.
1 I
mportance of
Geol
ogy in Dam Construction
376
nt roduct io n
376
8
. DAMS
37
1
7
.4 Tests for Rocks Used as
Aggrega
t
es
3 5 8
3 6 2
17
.2 Tests for Rocks Used as Foundation Sites of Constructions
1 7.3 Tests for Rocks Used as Building Stones
3 5 7
7 . 1 D
i
fferent Engineering Property Tests for Rocks
3 5 6ntroduction
356
7. ENG
l
NEER
I
NG PROPERTIES OF ROCKS
xiv
Contents
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Geo logy is the science of the earth (geo = earth, logos =
s t ud
y or science
)
. It deals with different
a
spects of the earth as a w h o le such as (i
)
origin, age, interior structure and history of
th
e earth;
(ii)
evoluti
o
n and
modi f i c
ation of various
s
urface
fea t
u res like
rivers , m ou n
tains and lakes along
w
ith
their causes; and
(iii)
materials making up the earth
.
G e o logy
is
a rela tively recen t s
ubjec
t.
I
n addition to its core branch es, advances in g
e
ology in
allied fields have led to spec ia lized sc iences like geo physics,
g e o c h e m i
stry,
geohydro1ogy
,
glac io logy
,
se i smo log
y , oceanography,
r
ock mec han i c s, pho
t
ogeology , and remote sens in g .
t
Similar
l
y
,
based on the applied importance of geology in o
th
er
f ie lds , re
l
a t
ed su
bjec
ts s u ch as
engineering geology, mining geology and so on h ave
c
ome into existence.
INTRODUCTION
A i
ms
: T he a
im
s of this chapter are:
1 .
T
o introduce the subject.
2.
T
o list out the main and allied branches of
geo logy
, explain their
s
ubject matter and to briefly
indicate their
r
elevance from the
c
ivi l engineering
poin
t of view
.
3
.
Toexp lore the scope of geology in terms of its academic s ign i f icance . It is purely meant to inculcate
interest and curiosity in
th
e subject
matter
.
4.
T
o give the importance of geology in the fields o
f:
(a)
e
xplo
r
ation, es
t imatio
n and ex
plo i
tation
of
e
conomic mineral depos i ts . and mining ; (b) ground water s t ud ies, t own
-
p lanning; (c) civi l
engineering, and so on.
Int
r
oducti
on; I.
I
Main and Allied Branches of
Geology
; I. I.
I
Physical Geol
ogy
;
1.1.2 Mineralogy
;
1.1.3 Petro
l
ogy; 1.1.4 Structural Geology
;
1.1.5 Historical G
e
ology
;
l.1.
6
Palaeont
o
logy
; 1.1.7 Economic Geology;
1.1.8
Engineering
Geology
; 1.1.9 Mining
Geology
;
I. I. I0 G e o p h ysics; I. I. I G eohydrology; 1.1.12 Geochemistry
;
1.2 Importance of Geology in Civil
E ngi
neeri
ng ; 1.3 Scope of
Geology
;
1.3.1 A ca
demic
I
mportance of Geology; 1.3.2 Importance of
Applied Geology in Differe
n
t F
i
elds.
GEOLOGY
1
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1
.1
.2 Mineralogy
This
de
als with the
s
tu d
y of
m
i
ner
al
s.
Minera l
s are basic
un
i
ts
w
ith whi
c
h
di
ffe
rent
r
o
ck
s
a
nd
o
res
of the earth are made up of. Details of mode of form
a
tion
,
composition
, oc
c
u
rrence
,
types
, a
s sociation
,
properties, uses, etc ., of
minera
ls form the
s
ubject matter of
mi
neralogy.
Knowledge in th is branch of geology
is
neces sary for a civil engineer because the properties of
rocks
- (
which he is g
o
i
n
g to make use
of
in different w a y s ) are to a
larg
e extent contri
b
ut
e
d by the
properties and composition of their constituent minerals. For example, s
om
etimes quartz
i
te and marble
resemble one another in shine, colour and appearance.
B
u t quartzite by virtue of its mineralcom
pos
it ion
is very hard, tough, s trong and
dur
able, while marble dis in tegrates and decom poses in a shorter period
b e
cause
of
its mineral
c
ompos it ion and properties.
1
.
1
1
Phy
s i
cal Geology
This is also variously described
a
s dy
n
amic
geo
logy. geomorphology,etc. As the
n
ame suggests it deals
with: (i
)
different physical features of the earth, such as
mo
untains, p lateaus, vall
e
ys, riv ers, l akes,
glac
iers
, and vo
l c anoe
s
i
n terms of their origin and
deve
l
opment
, (ii
)
the different c h
an
ges
oc c
urring
on the earth 's s
u
rface
,
like marine transgression
,
mar i
n
e regres s ion
,
formation or disappea rance
of
r ivers, springs and lakes, (ii i) geological work
of
wind, glaciers
,
rivers, oceans, ground water, and their
ro
l
e
i
n
co
nstant
l
y moulding the
earth'
s surface features, and
( i
v) natural phenomena like
l and s lide
s,
earth
q
uakes,
an
d weathering
.
The main
c
ause for s
u
rface changes is weatheri
n
g This is a natural phenomenon
resu l
ting di rec tly
o
r
indir
ectly
du
e to
change
s
in
t
h
e atmosphere.
I
t
dis
i
ntegrat
es and decomposes
rock
s
.
T h i
s
as pe
ct
i
s
of special importance from the civil engineering point of view,
b e c a u s
e colour,
appearanc
e, s trength
and durability of rocks are adversely affected by weath ering.
Thu
s even granite which
is
considered
ideal for most
of
the civil engineering w
o
r
k
s beco
m
es weak and friable on thorou gh wea ther ing.
re
n
derin g it u s el
e
ss.
Civil engineers d
e
al with structures like darns which are artificial barriers to the natu ral
fl
ow of
rivers. Proper understanding of the geological work of a river and its features will lead to thei
r
bett
e
r
utilization for engin
e
ering applications.
All
ie
d branches:
E ngineering geology
Mining
g
eology
Geophysics
Geohydrology
Geoch
e
m istry
Main
bra
nches:
Physical geology
Mineralogy
Petr
olo
gy
Structural geology
Historical geology (stratigraphy
)
Palaeontology
Economic geo
l
ogy
The vast
s
ubject of geology has been subdivided into the following branches for the sake of
s ys temat i
c
s tu dy:
1 .1 MAIN AND ALLIED BRANCHES OF
GEOLOG
Y
2 Textbook of Engineering
G
eology
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1
.1
.
6
Palaeo
ntology
If
,
u nder favourable conditions,
an ima l
or p
l
an
t
life
get
s embedded in
s
ediments, it will be preserved
partly or
c
ompletely. S
uc
h reli
c
s and remnants of ancient life pre served in roc
k
s
b
y natural
p
rocesses
are known as "fo s s ils". D e tails of the m ode of formation of fossi
ls
, their types, occurrence, etc. , form
the sub ject matter of palaeontolo
g
y.
L
ik
e stratigraphy, this is also
a
n importa
n
t branch of geolo
gy
.
though it
is
not of much importance from the civil engineering point of view. But as fossils are rare
1.1 .5
H is to
rical
G e
ology (
S
tratigra
ph
y)
T
he
earth
's sur
f
ace was a
l
w ays u n
eve
n and provided
s
u itab le conditi ons for the
depos iti
on of
sedime
n
ts
a
t
s
ome
p
l
ac
e or
th
e
o
ther
.
T h erefore
,
th
e
r
e are
s
edim
e
ntary
roc k
s
o
n
t
h
e earth
rep
r
esent
i
ng the entire
p
eriod of the earth 's
h i
s tory. Pr
op
er
in ve
stig
a
ti
o
ns of these rocks reveal the chronologi
c
al sequence
of formation of rocks,
evolu t i
on-migrati on -extinction details of different plant and animal life during
the
diff
erent periods of the
earth
's history. In
addit io
n , the
climati
c and geographical c hanges
inc lu
d ing
tectonic even ts in the geological
p
ast can also be known from these
inve
stigations. T h is kind of s tu
d
y
of th e
eart
h 's history through the sedimentary rocks is called historical geology. It is also ca l led
s
trati
graphy
strat
a
= a set of
sed im
entary
ro c
ks;
graphy =description) b e c a u
se th is subject d
ea l
s with
deiails and
de
scription of sedim entary rock sequences
.
This is a major branch of
ge
ology
, h
aving a
l
o
t
of ac
ademic
an
d applied importance. From the ci
v
il
e
n gi
ne
ering
poin
t
of vi
ew also it is relevant
that except for the fact th a t o lder
r
oc
ks are in general more stable (like sh ie ld areas of th e Arch
aea
n
era) and more competent due to more compaction and
cementat
i
on.
F
urther,
s
tudy of
s
tratigra
p
hy can
b e utilized in predic ting the
unde r l
ying s trata w h i
c
h m ay be very important in some s
pe
cific civil
engineering
con
s tructions .
1 .
1.
4
S
truc tural G eo
lo
gy
T he rocks w
h i
ch form
th
e
e
arth'
s c ru st undergo
v
ar ious de fo rma t io
n
s,
di
s locations and disturba
n
ces
under the inf luence of tectonic fo rces.
Th
e
r
esult is th e occurr
e
nce of
diff
erent geo logical structures
like folds, fau l ts , joints
a
nd u nconfo
rmi t i
es in rock s . The d
e
tails of m ode of forrnation,causes, types,
classification, importance,
etc
. , of th ese geological s truct
u re
s form the subject matter of structural
geology.
From the
c
iv i l engin eerin g poin t of v iew, it is as im portant
a
s
petro
logy because th ese geological
structures
mod
ify the inherent ph y sical
c
haracters of rocks
render in
g th
e
m more suitable or unsuitable
for civil engineering
purpo
ses.For example, at a d
a
m s ite s
e
d imentary rocks with upstream dip
provi
de
a
d
es
i rab
le
g
eol
o
gical set-up
, w h
ile t
h
e sam e r
o
cks with downstream dip make the geological set-up
m o
s t u ndes irable.
1.1 .
3
Petrolo
gy
Petr
o = rock,
lo
g
o
s =
s
tud
y
)
Petrology d
eal
s with the
s tu
dy of rocks. The earth 's crust, also called litho
s
phere, is made up of different
types of rocks. Petrology dea ls with mode of
fo rm
ation,
s
tr u c ture,
texture
, c
ompos
ition ,
oc
currence,
types, e tc
.
,
of
rocks.
T
h
e
compo
s
it i
o
n
an
d textural characters
o
f
roc k
s primarily
contrib
u
t
e to
t
h
eir
inhe
r
ent
s
trength
and durab
i
lity.
R
ocks b ased on their
sui tabi l
ity can be u
s
ed as foundation for dams, for tunnelling and
as materials of construc
t
ion. Hence th is
i
s the
m o s t
important branch of geology from the c
i
vi
l
engineering point of view.
Geology 3
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n 8 1
1 .
1
.
9
Mini
ng
Ge
olo
gy
T
hi
s deals with the
a
pplic
atio
n of
geol
ogical know
led
ge
in
the field of min
i
ng. A mining
e
ng
inee
r
is interes ted in the mode and extent of occurrence of ores, th eir association, tenor,
propertie
s, etc. It
i
s also necessary to know oth
e
r ph
ys
ica
l param
eters
li
ke d
e
pth, direction (strike),
i
nclination (d ip),
thi
ckness and reserve of
or
e bodies
f
or efficient utilization. Such details of min
e
ral
e
x
p
loration,
estimation and e
xploi
tation are dealt with in mining geo
l
ogy.
The
i
m
po
rtance of geology
i
n
minin
g
m
ay be cited with the following
example
. Sometimes, the
lode
s or seams of
economi
c min
e
ra
l
s sudd
e
n ly
ge
t
terminated
. This
mig
ht happen e ither due to the
natural
l
imit of the ore body or
du
e to f
aultin
g. Geological s tudies will
solv
e
this p
ro
blem and, if it
1 .1.8 Engin
ee
ring Geo
l
ogy
This
deal
s with th e application of geol
ogi
cal
knowledg
e in th e
fi
eld of civil
e
ng
ineering
, for
exec
ution
of safe, stable and
eco
nomic
c
onstructions like
dam
s,
brid
ges and tunn
e
ls .
A
s
thi
s
i
s the branch with
whi
c
h we are most
co
n
cerned
, it has been
e
xplained
i
n
de
tail separately (refer to
S
ec. 1 .2) .
1.
1
.7 Economic Geology
Mi
nerals can be
gr
ouped as
g
enera l
rock-f
orming
mi
ne
r
als
a
nd economic
mi
ne
ral
s.
S
om e o
f
the
economic minerals like
talc
,
gr
a
ph i
te, mica,
as
b
estos
, gypsum,
m
agnesite, barytes,
dia
mond
a
nd gems
are useful
a
s
suc
h or as
r
aw
material
s in different indus
trie
s
.
Some
other
s
lik
e hem
a
tit
e , c
hromite,
galen
a
and pyro
lus
ite
a
re used
a
s ores for the extr
a c t
ion of various
meta
ls, the uses of whi
c
h are well known.
Th
e prosper ity
o
f a nation depends
t
o a
l
arge ext
e
nt on the
ric
h
res
erves of economic mineral depos its
i
t
ha
s. (
F
or
e
xample, Gulf
c
ountries are rich
be
cause of th
e
ir oil deposi
t
s;
S
outh
Afri
c
a
i
s rich because
of its
go
ld and d
i
amond de
po
s its.)
The
det
ails oftheir mode offormati
on, occ
urrence, c
l
a s s
if ic
ation
,
associ
a tion,
varieti
e
s
, concentration
,
p
ro
perti
es
, uses, etc. , fo rm the subject
matt
er of "econo
m
ic
ge
o
l
ogy". This branch of ge
ol
ogy, though
it
i
s very
imp
o
rtant by v
irt
ue
o
f
i
ts
econ
o
mic
im
port
a
n
c
e
, is no
t r
elevant
f
or
civ
il
enginee
rs for
o
bv
iou
s
reasons. It will be enough for them to know a few deta
il
s as in the
c
ase of fossils, so that they will
not be ignorant of
the
m as and when they
c
ome
a
cross these
i
n course of their civil engineering works
like tunnelling and
ro
ad
c
ut t ing.
E
ac
h of the
fo
rego
in
g b
ra
nches deals with specific subject matter and comprises the
m
ain branches
of g
eolo
gy proper . Furth
er
, based on
applicati
on of g
eol
ogical knowledge in
othe
r
fiel
ds there
ar
e
man
y
other all ied branches co
ll ec ti
vely called
e
arth sci
e
nces.
Some of them d
esc ri
bed here are:
En
gi
neering geo
logy.
Minin
g geolo gy.
G
eophysics
.
Geohydr
ology.
G
eochemis try.
a
nd
thr
ow much
li
ght on
th
e
pas
t history of
th
e earth
,
a
civil
en
gi
neer should know s
om
e d
etail
s
r
egarding them so that he recogn
i
zes them as
foss
il
s . Whenever he c
o
mes
a
cross such finds
duri
ng
h is w
ork
, he
sh
ould
re
port
th
e m atter to th e person
concerned
,
fo
r
necess
ary act
i
on.
4 Te
xtboo
k
o f
E n
g
in ee
ri
ng G eolo gy
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The civil en g
i
neers
ai
m
a
t s
afety,
stab
i
lity, e
c
onomy and life
of th
e
s
tructures that they construct.
Civil
engineering co
ns
t ruc tions
l
ike dams
a
nd b ridg
e
s w ill have their fo
u
ndations on geo
l
ogical formations
of the earth's surfac
e
.
Therefore
, their
s
t
abi
lity
a
nd
s
afety depend on the competence of the in s
i
tu
rocks of t
h
e s ites
concerned
. A
l
s o ,
t
o be
econom
ical, s
u
ch competent foundation rocks s
h
o
u
ld be at
a shallow d
e
p
t
h
.
Further
,
fo
r
h u ge con
structi
on
s
l
ik e
dams, b u i
l
d
i
ng materi
a
l
s
are required in very large
1.2 IMPORTANCE OF GEOLOGY IN
C
IVIL E NGINEERING
1 .1
12
Geoc
he
m
is
try
This b ranch is r
e
lative
l
y
mo
re recent and deals
wit
h the oc
c
urrence, distribut
i
on , abundance, mobil
i
ty,
etc.,
of
different
element
s
in the
earth'
s
c
ru
s
t.
It
is not important
fro
m the
c
i
v
il
engi
n
ee
ri
ng
p
o
i
n
t
of
view.
1.1.
11
Geo
hydrology
Thi
s may
a
l
s
o be called
a
s hydrogeology.
I
t
dea
l
s with
occurrence, moveme
n
t
and nature
(i.e , qual
i
ty
and
quantity
) of ground
wate
r in an area. It
h
as a
p
plied importance because ground
w
ater
h a
s many
advantage
s over surface water. This b ranc
h i
s
c
lo
s
ely related to geo
l
ogy becau se the very
exis
tence,
m
ovement of ground water,
etc
. , are directly rela
t
ed to
p
orosity, permeability, structure, texture and
composition of the surface and underground roc
k
s. Dy
ke
s may control t
h
e occurre
n
ce
an
d movement
of ground water. In
general
, geo
l
ogical, geophysical (electrical
res
istivity method)
an
d hydro
l
ogical
s
tudies are
t
o
gether taken
u
p for ground
wa
t
er
i
n
ve
s
tigat
ions.
1 .1.10 Geophysics
The study of ph y
s
ical properties like density and magnetism of the earth or
i
ts parts, to know i
t
s interior
,
forms the subject matter of geophys
i
cs. Broadly it is subdivi
d
ed i
n
to general (or pure) geop
h
ysics and
e
x
ploration (or app
l
ied) geophys
i
cs.
P u
re
geoph y
s ics deals with genera
l
aspects of the earth as a
whol
e
and
explor
ation geo
ph y
s
ic
s
deal
s with the
s
tudy of u
p
per
la
yers of the
earth
's crus t inorder to (i
)
solve
so
m
e civil engineering
probl
e
m
s, (ii) locate oil and goes
deposits, (
iii) locate grou nd water
, (
iv) explore
an
d
es
timate the ore depos its, etc., of u
ndergr
ound.
The
re are different types of geophys ical
investi
gations based on the
ph
ysical
pr
operty utili
zed
,
vi
z
. grav
ity
methods
,
s
eismic meth
od
s,
magn
etic
methods. Since these are quic
k
ly and easily done on t
h
e surface, large areas can be investigated
economically and
efficientl
y
.
Engineering
geoph y
s ic s is a bran
c
h of exploration
geo ph y
s ic s which aims at s
o
lvin g
civ
i l
engineering problems by in t
erpreti
ng s
u b
surface
ge
ology of t
h
e
area
s concerned.
Geoph y
s
ic
al
investigations are very u
se
ful
in
solving foundation problems, alignment of
struct
u res, leakage
probl
em
s
alo
ng canals, locat
i
ng building materials like stones (where they are not available on the
s
urface
), etc. E
lectric
a
l
resistivity methods and seismic
refraction method
s are commonly used
i
n
s
o
l
v
in
g c i
v
il engineering
p
roblems.
is due to fau
l
ting, the continuity can be traced by ascertaining the
d
irection and extent of displacement
caused by fau
l
ting.
The geological knowledge
h el
ps in planning the
me
t
hod of mi n ing or
quarrin
g a depo
s i
t
in
an
advan
t
ageous way.
Geology S
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With Reference to Reservoirs
Th
e
J
erome reservoir of Idaho and the
H
ondo reservoir of New Mexico are two examples of failures
due to geological reasons.
As in the case of dam sites, se
l
ection of suitab
l
e sites for locating reservoirs needs geological
studies to make them successful. Unfavourablegeological conditions lead to quick siJtiog of reservoirs,
th
ere
b y decreasing its life, and profuse leakage of stored
water.
Intense weathering in the rocks upstream causes silting prob lems . Porosity
an
d permeability
of
rocks, occurrence
of
fau l t s
, joints and other weak
p
lanes ca
u
se leakage
prob lems
. Grou
n
d water
co
n
ditions also play a key ro
l
e
i
n
i
n
fluencing
l
eakage
.
Th
u
s proper
s tu
di
es
of
geological conditions
at any proposed
r
e
s
ervoir site will fo
r
ewarn a
n
en
gin ee
r of the prob
l
ems,
if
any.
With Reference to Tunnels
R
amganga diversion tunnel
(
Hi
m a l a y a s )
,
U m i a m -
Barapani stage
I tu
n
n
e l
( Megha laya ) ,
Key
n
a ID stage
tail race t unne l , and B a s s ein creek tunnel (Bom
b
ay) are some
of
th e e
x
amples where geolog ical
c
o
nd
itio
n
s posed
se r i
ou
s
p
rob lems.
C o m p e
te
nc
e of the roc
k
s , associated
g eo
logical structures like
b e d d i
n
g, fau lts, joints, porosity
an
d
permeability of rocks, and ground water conditions are the geological c
o
nditions w h ich
n ee
d to be
t
h o
roughly s tu died to solve such problems.
With
Refe
rence to
D a 1 1 1 s
T
he fo ll owing are a few examples
of
fail
u
res of
d
ams. T hese failures have occurredonly due to adverse
geological conditions a
n
d not due to technical lapses:
l. St. Francis dam of California.
2
. Lafayette
d
am of California.
3
.
A u
s
tin dam
of
Texas
.
In
addition to these
fa i lures ,
there are
a ls
o a
n u m b e
r of examples w here the cost of construction
b
ecame very high in order to overcome the associated geological drawbacks.
Hales
b
ar dam (
o
n Tennessee
r
iver) , Camarassa
d
am (Spain), Dokan dam (Iraq); Chickm a
u
ga dam
(USA), Val l G allina dam (Italy) are a few examples of this kind.
The aforementioned exam
p
les amply illustrate that serious conse
q
u
ences are likely to resu lt if
proper attention is no
t
paid to the geological conditions occurring at the dam site.
Geological studies at the dam site will also suggest which design will be suitable for a given
geological context.
F
o
r
example,
grav
ity dams need very strong and competent fou
n
dation
roc
ks; for
buttress
d a m s ,
relatively less strong foundation rocks are
enoug
h ; arch dams
n ee
d very strong and stable
abutment
rock
s; for earth dams, even weak
foundatio
n rocks meet
t
h
e
r
e
quire
ments.
qu a
ntities near the
s
ite. Otherwise, the cost of construction will increase.
Thes
e critical details of c ivil
engineering importance, i
.e .
, durability and competence of foundatio n roc
k
s, their depth
of
occurrence,
availability of b u i lding material near project s ites, can be re lia
b
ly
ob ta ine
d from
g eo
logical a
n
d
geophysical studies .
The significance of geology w ith reference to civil engineering w il l be better appreciated if the
consequences of ignoring geological studies are also
quo ted
. Therefore, a few specific e
x
amples of
fa i lures of
d
iffe
r
ent kindsofimportant
c iv il
constructions are
li
sted now. Further details ofthese failures
are given unde
r r
e
s
pective chapters.
6
Textbook of Engineering Geology
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1.3 .
1 A cadem ic
Im
portance of Geo
l
og
y
The stu dy
of
details of academic s ignificance of geology
is
no t
w it
h in the p
u rv
iew
of
the subject of
enginee
ri
ng geo
l
ogy.
B u
t at the same
ti
me,
i
t
i
s worth knowing from cu rios
i
ty and
i
ntere
s t po i
nts of
view some
o
f the
u nb e
lievable
a
nd s
tart
l i
n
g
fac
ts
ab
out
ou
r earth a
n
d its his to ry
,
which
a
re given as
follows:
I. The H im alayas, the tal lest m o
u n ta in
s
of th
e
p
rese
n
t d
ay
, are relati
ve
ly
o
f rece
n
t geological age
whose
grow
th was witnessed by m an . They are m ade up of mar ine
fo rmat ion
s s ugges ting th at t
h e
ir
p lace w as once occupied b y a narrow sea
(Tethy
s).
G
eol
ogy
is
one of the
m o s t
in
t
eresting and useful su bjec ts for the
l
ayman and the knowledge
ab l
e
peopl
e
alike. This is the only su b ject which gives information about the earth. Some
of
the details regar
di
ng
its
ac a
demic and
a
pplied im portance are
a
s follows.
1.3 S C
OP
E
O
F GEOLOGY
With R
eferen
ce to Roads and
R
a
ilway
s
The erstw h ile problem of freq
uen
t bou ld
erfa
lls al
on
g some sections of Bor G
h
at
o
n the Bombay-Pune
line
is
one of the examples that may be quoted to highligh t the importance of geological studies at
the s
it e .
Thus, to
ens
u
re safety
,
s t ab i lity
,
s
u
c c e ss
a
nd eco
n
omy i
n a
l l majo r civil
en
gineering co
n
structio
n
s ,
geo
log
ical
s t
u d ies are very important. The most im portant
an
d common geol
og i
c
al fa
c
tors
wh
ich
co
n tr i
but
e to the
s
u
i tabi l i
ty or
unsuita
b il
i
ty of a
s i
te for a given pu rpose are existing
roc
k types,
as
s
ocia
t
ed geological
s
truct
u
re
s and ground
wa
t
e
r con
di
tion
s
.
Occ
u r rence
s of
l
ands li d
es
,
earth
qu ak
e
s,
land
s
u b s id
e
nces, high snowfall,
w ate rl
ogging, type ofnatural forces like rivers,
e
t
c., at the propos
e
d
s ite are some other geological factors w
h
ich may need spec ial study f
o
r taking
p
recautio
n
ary measures.
Geological know l
e
dge can also be utilized w h
e
n n
ec e
s sary in dea ling with h uge b u ildings,
runways, te
rr
ain
eva
lu
atio
n for military operation
s
and d
efe
nce purposes.
It is to
b
e borne in mind that the role of geology in civil e
n
gineer i
n
g is to
in d
icate (at
d
ifferent
stages like d
e
signing
a
nd con
s t
ruction) in adv
a
nce the existing
draw
b acks, if
a
ny , of the sites, so that
suitab
l
e precau ti onary steps are taken to
over
come them and sites are
m a
de safe for u n
de
rtaking
cons truction.
It
i
s no
t
a
ru l
e that
geo log i
cal
co
nd
i
ti o ns
s
h ou ld be adverse e
veryw
h
ere
,
th o
u gh in practice ideal
s it
es are rare. Failures of
vario
us
earl
ier
struct
ures due to
di f fe re
nt
geo l
og
i
cal causes
h
ave now made
it m
a
ndatory to have
geologic
al clear
a
nce before taking up m
a
jor con s tr u c tions.
This
w ill
ens
u re risk
free
i
nvestment of time,
m o
ney and
ene
rgy.Nat
i
onal organizations like the Geo
l
ogical Su rvey of In dia
an
d the Natio
n
al Geop
h y
sical Research Institute
d
o t
h
e
n
eedful in th is regard.
With R
ef
erence to Bridges
The failure of a bridge near Cornwall (Canada
)
and
di f f icu
lti
e
s faced in the con s tr uction of the Georges
ri
ver b
r i
dge il lustrate the consequences of im proper or
incom
plete study of geo
l
og
i
cal cond
i
tions of
th
e s ites concer
n
ed.
S
tro
n
g
an
d
s
t ab l
e
ro c k
s are
n eed
ed for
fou
n
da
t
io
n
s
an
d
ab
utme
nts. Adverse geo
l
ogical
s
tr u
ct
u
res
sho
u
ld
no
t occur
a
t the
site
.
Geolog
y 7
-
7/23/2019 Enginnering Geology- N Chennakesavulu
17/407Lopynghted m2tennl
2.
T
he Indo
-G ange t i
c
plain s ,
the most fertile la
n
d of our co
u
ntry, and the seat of power of many
dynasties are su rprisi
ng
ly of th e most recent origin in geologica l t e rms .
3.
In contrast to this, the D eccan
p
lateau, w hich is ad
j
acent to the Indo-G a
n
getic
p
la ins , represe
n
ts
the oldest age and may be a piece of the primordial
crust
i
tsel
f.
4.
Th
e fossils pr
e
se
n
t i
n rocks of different geological ages
provid
e
c
o
nvincing proof of evol
u ti o
n
of
life from the beg inn in g to the present d
ay
. L ife originated in the sea and then extended to la
n
d.
Th
e trend was as follows:
s
o
e
>- U
n g
8 s
: : > "
e s
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n 8 1
P
r
operti
es and Uses
C
hamockit
es are
hard
, s trong
an
d durab
l
e roc
k
s with a high
lo ad
-bearing
capacity
. Like
o
ther
pl
utonic
rocks t
h
ese are also
n
on-porous and
impermeable
. They do not have
a
ny weak
p
lanes like
bedding
,
s ignificant banding or foliation. They are suitable for
a ll
civil engineering wor
k
s . H
o
wever, their colour
is
b
lackish.
M
ahabalipuram temples (Tamil Na
du
) were constructed many centuries ago from
charnoc
kites.
The
chamockite
s of peninsular India are claimed to
b
e
o n
e
among
st
th
e stronges
t
and the most
durable s tones of t
h
e
wor
l
d
.
Structure and Texture
Li
k
e other
p
lutonic rocks
chamockite
s also are
compac t
, massive, dense and
n o n
-porous (
imperviou
s ) .
Texturally, these are
phane
ric coarse
g
r
a
ined. Fol
i
ation and bandi
n
g
o
c
c
ur sometimes o
n
ly for s hort
l
e
ngths.
A
vailabili
ty
C
harnockite
s
,
w h
ich are Archaean in age , occu r
w i
d ely d
i
st
ri
buted in peninsu
l
ar India and form a
portion o
f
the Nilgiri hills and so
u
thern parts
of
the
E
astern and W e
s
tern gh
a
t
s . Ta
mil Nadu
,
Karnatak
a
a nd
,
to
s
ome
extent
,
A
n
dhra Pradesh have
l
arge and good
ou
t
cro
p
s
of
c
ha
rn oc k
ite
s
.
Appearance
of
C harnockite in Hand Specim ens
Mega
s
copically, i.e. , in hand spec i
m
ens, all c
h
amocki
t
es, irrespective of
t
heir composition,
ar
e
melanocrati
c , i.
e.
, b lack coloured. All are p
h
an
e
ric coarse grained and equigranular with shining laths
of f
e
l
d
spar.
l
n acidic varietie
s
, greasy looking bluish grey quartz oc
c
urs.
Mine
rals
Presen t
A
ll chamoc
kite s
ar
e cha
r
acteri
z
ed by an abundance of feld spars and
pyroxenes
, particularly
h y
persthene.
Acid
i
c chamockites are like hypersthene
granite
s
, rnineralogically,
i.e.
,
they
ma
in l
y contain
feld
s
par
s,
quartz and hypersthe
n
e. The
i
n
ter
media
t
e and basic types are equivalent to
qu
artz norites and norites
res
pecti
v
el
y
. (Norite is like gabbro. The
d
iffere
n
ce
i
s t
h
at the
py
roxene present in gabb
r
o
i
s
augit
e,
but in
nori
te the pyroxene is
hypersthene
. Both have the la
b
radorite type of plagiocl
as
e
f
eldspar in
addition.) T
h
e ultrabasic ( i .
e.
, silica-poor) type of chamockite is
e
quivalent to pyroxenite.
Mode of Origin
Though chamocki
t
es are con
s
idered as igneous rocks, they
s
how peculiar characters diagnostic of both
igneou
s and
met
amorphic rocks. Hence
t
here
i
s a controversy about their origin. Throwing off tongues
and veins
in
t
o
surrounding rocks b y the
c
hamoc
ki
te body and occurrence
of
features
ind
icative
of
partial
a
ss
i
mi
l
ation
an
d
h
ybri
d
ism
strong
l
y support
t
h
e intrusive and
igneou
s origin
of
c h
amockit
es
.
But (i)
t
he occurrence (though occ a
s
ion
a
lly) of typical metamorphic minerals Like cordierite and garnet,
(i i)
th
e occurre
n
ce of gneissose stru c tu re
, (
ii
i
)
t
he myrmek itic growth of quartz and
fe l
dspar and
(iv
) sporadic
ro
und quartz grains
en
closed by
fe lds
par
s
tr
o
ngly support the metamorphic
or
igin
o
f
charnockite
s .
Cbamockites are believed
t
o have been formed
o
ut of recrys l31lization of igneous roc
k
s
u n d
er
condition
s of
high temperature and
pre
ssure (i .e.
, of
p
l
utonic
metamorphi
sm).
in colour and texture. These genetically related rocks are called c
h a
mockite series. This series
i
s a
l
so
call
e
d N il
g
iri gneiss or mountain
gneis
s .
Ig neous Rocks 13 3
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n 8 1
Pressur
e
The pressure
w h i
ch
cause
s metamorphism
i
s of two different kinds, namely, uniform pre
s
sure and
dir
ected pressure. .
Uniform
pre
ssu r
e increas
es with depth (i.e., with increasing overburden), I
t
acts vertically
'
do
wnw
ards and affects the
volum
e of both liquids and solid
s
. Naturally, its effect is significant only
at great depths, but not at or near the surface. This also means that high temperatures will also be
as s
o
ciated (d u e to th e depth fac tor) with high uniform
p
ressure. So, both of them act together
an
d
bring about
m
e tamorphi
s
m in rock
s .
T
e
m p
e
ratur
e
The source of temperature w hich is res
pon
s ible for metamorphism is either due to depth or due to
the contact with magma (i.e., magma chamber or magmatic intrusion). The metamorphic changes
mainly take place in the temperature range of 350
-
850 C. The temperature rise also increases the
c
hemical
acti
v
ity in rocks and
f ac i
l
itates reacti
o
ns during metamorphism.
8.1 .
1
Metamor
phi
c
A
gents
The process of metamorphism occurs in rocks due to the effect of high temperature, pressure and
c
hemic
a
lly active fluids. These three are known as metamorphic agents. Generally, all these three
a
ct
tog
ether and
cau
se meta
morphis
m.
But
, sometimes, any one or two of them may dominate and p
la
y
an active role. The
follow
ing are a few relevant details about metamorphic agents.
The word metamorphism means c
h
ange of form
m
e
ta =
change;
morpb =
form).
In
petrology, it
indicates the e
c
t
of
temperature
,
pres
s
ure and chemically active s o lutions over the texture
,
minerals
and compo
s
ition of parent rocks. Igneous and sedimentary rocks which serve as parent
r
ocks are formed
und
e
r a certain
phy
s
i
cochemical
enviro
n
ment,
i
.
e
.,
at the
t
i
me
of
their formation, they were
in
equilibrium with their
surroundin
gs in terms of temperature, pressure and chemically active fluids
.
Subsequent to their formation,
i
f any of these fac
to
rs c hanges significantly, the equilibrium gets u pset
and necessary metamorphism, i.e , textural, compositional and m ineralog
i
cal c
h
anges take place to
create a new equilibrium. This means the constituent minerals, texture and composition of parent rocks
b y
metamorphis
m change over to new minerals or new textures or new compositions which are more
s
table and
s
uitable under new conditions. For example: As a result of metamorphi
s
m (i)
gra
n ite, one
of tile mos
t
abunda
n
t igneous rocks, changes to granite gneiss; (i i) periodotite, an
u l
trabasic igneous
rock, changes to serp
entin
e and talc sc
h ist
; (iii) gabb
r
o (or
dolerite)
, an intermediate igneous rock,
ch anges into
hornbl
ende
schis
t. Among sedimentary rocks (iv)
sandston
e changes into quartzite;
(v) limestone
c
hang
es into
marble
;
(
vi
)
s
hale changes into
s
late and
s
o
on.
The
ran
ge
of
temperatur
e
and
pre
ssure w h ich occurs
i
n nature is very w
i
de
.
The normal surface
te
mper
a
tu
re and pre
s s
ure affect the rocks by
caus
ing weathering At the other extreme, intense heat
in the
s
ub
s
urface
(
at great
depth
s) melts the ro
c
ks and produces magma. As accepted by many, the
term
m
etamo rph i
s
m does not include either weathering of rocks or magma formation. The extreme
s tate
s
of
metamorphi
s
m ar
e
represented by palingenesis or
ultrametamorphi
sm
or anatexi
s. In these
the
inten
sity of temperature and
pre
ssure will be
s
o high that it
involve
s partial melting and mixing
of rocks. Since the identity of the altered
roc
ks
i
s not totally destroyed, in these
s tates
, they come under
metamorph
is
m
They are next only to the formation o
f
new
magma
8
1 MET
A
MORPHISM
162 Tex
tbook
of
E ng
ineering
G eo lo
gy
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~~
c
"tl .
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Case
I: When beds d
i
p in the direction opposite to the s
lo
pe o
f
the valley: V po ints
u
p the
va ll
ey
.
Case 2 : When beds
d
ip in the same di
re
c t ion as the
s
lope of th e
v
alley
an
d at a greater angle:
V po ints
down
the
vall
e
y .
C ase 3: When beds are horizo
n
tal or dip
i
n the same
dire
ction as the s lope of the valley and
at a
smal le
r angle: V p oi n ts up the va l ley and is longer than in Case I.
Fig.
9.2
Valleys and
s
hapes of outcrops
Case 3
1 0 0 0 i;'"~~ti:::::. . . .
J
r T
T
500
,_
Case 2
500
1000
Case 1
500
1000
any direction
a
l features.
H e n c e
, such rocks even if fo lded or faulted do not provide any indication
of
them. Therefore, they are unsu i t ab le fo r study
of
geological s t ruc tures . For a similar r ea son ,
metamorph ic rocks , such as m a r b les and qu artz ites, which bear a predominantly granulose s t
ru
cture,
are also unsuitable for
t
he s tu dy of th ese
type
s of
st ruc ture
s.
Structural Geolog
y