SOLVE

Objective:

Draw a geological cross-section along XY.
Determine the Dip and Strike of the formations.
A horizontal tunnel is proposed at an altitude of 1200m.

Pre-requisites:

Topographic map

Description True and Apparent Dip: Apparent dip is the inclination of geologic beds as seen from any vertical cross section not perpendicular to the strike of the geologic beds. When a vertical cross-section is perpendicular to the strike of the beds, the inclination seen in the cross section is called the true dip.

Angle of Dip: is the angle made by the Earth’s magnetic field lines with the horizontal.For any tilted bed, the dip helps in the providing the steepest angle of descent relative to a horizontal plane. The angle of dip is represented between zero degrees to 90 degrees

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.

Points	X-Co	Y-Co
a	x1	1300
b	x2	1400
c	x3	1500
d	x4	1600
e	x5	1600
f	x6	1500
g	x7	1400
h	x8	1300
i	x9	1300
j	x10	1400
k	x11	1500

STEP 3

Identify X-axis and Y-axis taking X as origin and define scale.Mark X^' at a height of 1000 as the new x-axis.

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’(1535,0) on the graph.

Points	X-Co	Y-Co
a	30	1300
b	140	1400
c	290	1500
d	450	1600
e	550	1600
f	690	1500
g	840	1400
h	960	1300
i	1050	1300
j	1190	1400
k	1380	1500

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
u	x6	y6
v	x7	y7
w	x8	y8
x	x9	y9

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
u	x6	y6
v	x7	y7
w	x8	y8
x	x9	y9

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.

▼ ▼ If Found If Not Found

STEP 8

Calculate the index value of all solid lines.

Hint: Found

Hint: Not Found

Points	X-Co	Y-Co
a	30	1300
b	140	1400
c	290	1500
d	450	1600
e	550	1600
f	690	1500
g	840	1400
h	960	1300
i	1050	1300
j	1190	1400
k	1380	1500
Y'Axis	1535	1600

Table 2
Points	X-Co	Y-Co
p	50	y1
q	190	y2
r	360	y3
s	650	y4
t	810	y5
u	940	y6
v	1095	y7
w	1250	y8
x	1410	y9

➤For the solid line p:

STEP 9

Plot the above points (p to x) with the plotted points (a to k) along with the points Y’ (1535,0) on the graph.

Points	X-Co	Y-Co
p	50	1318
q	190	1433
r	360	1544
s	650	1529
t	810	1420
u	940	1317
v	1095	1332
w	1250	1432
x	1410	1519

STEP 10

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

STEP 11

A horizontal tunnel is proposed at an altitude of 1200m from the x axis parallel to it, between the bounds.

STEP 12

Calculation for Angle of dip.

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

STEP 13

From the points (p,q,r,s,t,u,O,M,N) find angle of dip θ

Points	θ(°)
p
q
r
s
t
u
v
w
x
O
M
N

STEP 13

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

➤p-p’☚

➤q-q’☚

➤r-r’☚

➤s-s’☚

➤t-t’☚

➤u-u’☚

➤v-v’☚

➤w-w’☚

➤x-x’☚

➤o-o’☚

➤m-m’☚

➤n-n’☚

STEP 14

Location of Types of stones on the contour.

➤LimeStone☚

➤Shale☚

➤Redsandstone☚

➤Standstone☚

➤Conglomerite☚

Profile View Graph

Contour Map Geographical Profile along XY

CONTOUR MAP

Objective:

Pre-requisites:

Profile View Graph