SOLVE

Objective:

Draw a geological cross-section along XY.
Determine the downthrow of the fault.
A road is proposed as shown in the map.

Pre-requisites:

Topographic map

Description Folds: The term fold is used in geology when one or a stack of originally flat, level surfaces, such as sedimentary strata, are bent or curved as a result of pressure and high temperature.

Anticlinal folds: Anticlines are folds in which each half of the fold dips away from the crest.

Synclinal folds: Synclines are folds in which each half of the fold dips toward the trough of the fold.

Fault: Faults are fractures (cracks) in rocks along which movement has occurred.

Dyke: A dyke (or dike) in geology is a type of later vertical rock between older layers of rock.

Ductile: When rocks bend or flow, like clay, it is called ductile deformation.

STEP 1

Identify the line about which the profiles are to be drawn.

Line to be considered for profiles to be drawn:

XY

STEP 2

Mark all the points of XY line that is obtained by the intersection of the dotted line with this XY of the contour map. (except the road part shown by points c and d).

Points	X-Co	Y-Co
a	x1	100
b	x2	200
c	x3	N.A
d	x4	N.A
e	x5	300
f	x6	400
g	x7	500

STEP 3

Identify X-axis and Y-axis taking X as origin and define scale.

STEP 4

Plot the points taking its distance from X as x coordinate and the index values of the corresponding line as y coordinate along with the points Y’(1520,0) on the graph.

Points	X-Co	Y-Co
a	120	100
b	490	200
c	780	N.A
d	820	N.A
e	870	300
f	1150	400
g	1480	500

STEP 5

Mark all the points of XY line that is obtained by the intersection of the solid line with this XY of the contour map.

Points	X-Co	Y-Co
p	x1	y1
q	x2	y2
r	x3	y3
s	x4	y4
t	x5	y5

STEP 6

Name the points as p,q,r … respectively taking its distance from X as x-coordinate.

Points	X-Co	Y-Co
p	x1	y1
q	x2	y2
r	x3	y3
s	x4	y4
t	x5	y5

STEP 7

To Calculate the index value of the solid line.

➤Search for the first dotted line on both the sides of the solid line.Let their index values be M and N.

➤Let α be the x-coordinate for dotted line with index value M from Table 1

➤Let β be the x-coordinate for dotted line with index value N from Table 1

➤Let ¥ be the x-coordinate for selected solid line from Table 2.

➤The index value of the solid line is given by

➤For α>β:Index= (N*(α- ¥)+M*(¥- β))/( α- β)

➤For α<β:Index=(N*(¥- α )+M*( β-¥))/( β- α)

STEP 8

Calculate the index value of all solid lines.

Hint

Table 1
Points	X-Co	Y-Co
a	120	100
b	490	200
c	780	N.A
d	820	N.A
e	870	300
f	1150	400
g	1480	500

Table 2
Points	X-Co	Y-Co
p	270	y1
q	520	y2
r	925	y3
s	1180	y4
t	1450	y5

➤For the solid line p:

STEP 9

Plot the above points (p to t) with the plotted points (a to g) along with the points Y’ (1535,0) along with u(710,240) on the graph.

Points	X-Co	Y-Co
p	270	140
q	520	208
r	925	320
s	1180	410
t	1450	490
u	710	240

STEP 10

Join all the plotted points on the graph free hand. And extrapolate it between the bounds.

STEP 11

Mark road points on the cross section c(780m,280m) and d(829m,290m).

STEP 12

Draw a line perpendicular to X-axis passing through POINT J’(710,0). which is the fault line that is FF, that’s cuts the curve at POINT u(710,240).

STEP 13

Calculation for Angle of dip.

➤Search for the points of intersection between the solid line and the dotted line on the contour map.

T1=100 T2=200

T2>T1

Angle of Dip
θ=27°

STEP 14

From the points (p,q,r,s,t,u) draw a line at an angle θ with horizontal in clockwise direction and its point of intersection on x-axis be (p’,q’,r’,s’,t’,u’) respectively.

➤p-p’☚

➤q-q’☚

➤r-r’☚

➤s-s’☚

➤t-t’☚

➤u-u’☚

STEP 15

Location of Types of stones on the contour.

➤Conglomerate☚

➤Course grainded Sandstone☚

➤Fine grainded Sandstone☚

➤Shale☚

➤Limestone☚

STEP 16

Determination of downthrow of the fault.

Profile View Graph

Contour Map Geographical Profile along XY

CONTOUR MAP

Objective:

Pre-requisites:

Profile View Graph