This document defines and describes different types of unconformities in geology. It begins by defining an unconformity as a break or gap in the geological record representing a period of erosion or non-deposition. It then describes the major types of unconformities, including angular, disconformity, non-conformity, and local unconformities. Finally, it outlines several ways that unconformities provide significance, such as indicating time intervals missing from the geological record, structural discordances between rock layers, evidence of past topography, and signs of weathering at the contact surface.

2. CONTENTS….
 Introduction
 Definition
 Plane of unconformity
 Types of unconformities
 Signification of Unconformities

3.  It is one of the most common Geological structure
found in rocks.
 Unconformity = Gaps in rock layers
• From when layers of rocks are removed by erosion.
• From when a period of time passes without any new
deposition to produce new layer of rock.
Introduction

4. Definition
 A surface that represents a break in the rock record.
 An unconformity may be defined as surface of the
erosion or non-depositions occurring within the
sequence of rock. An unconformity is developed due to
the changes in the process of deposition of rocks.

5. Plane of unconformity
 plane of unconformity is which the separation is a
underlying (older) and overlaying (younger) rock
strata's.
plane of
unconformity

6. Types of unconformities
 Angular Unconformity.
 Dis -conformity.
 Non-conformity.
 Local unconformity.
 Blended unconformity
 Para conformity
 Buttress unconformity

7. Angular Unconformity
 When the underlying (older) and overlaying
(younger) rock strata's show some angle with respect to
one another i.e. Angular unconformity.
Y.R.B.
P.O.U.
O.R.B.

8. Disconformitiy
 When underlying (older) and overlaying (younger)
sedimentary rock strata's are parallel and contact
plane is an erosion surface is called Disconformities
Y.R.B.
P.O.U.
O.R.B.

9. Non-conformity
 When underlying (older) rock are igneous or
metamorphic and the overlaying (younger) rock are
sedimentary this types unconformity is called
Non-conformity.
 Y.R.B.
 P.O.U.
 P.O.U. O.R.B.

10. Local Unconformity
 It is similar to Disconformities but Local in extent and
a short period of non-deposition.
 The age between the underlying (older) and overlaying
(younger) strata are very less this type of unconformity
called Local unconformity.

11. Blended unconformity
 An unconformity having no distinct surface of
separation or sharp contact ,as at an erosion surface
that was originally covered by thick residual soil,
which graded downward into the underlying rocks and
was partly incorporated in the overlaying rocks.
Overlaying strata
P.O.U.
Underlying strata

12. Para conformity
 A Para conformity is a type of unconformity in which
there is no evidence of a gap in time, because the
planes above and below the gap are parallel and there
is no evidence of erosion.
Y.R.B.
P.O.U.
O.L.B.

13. Buttress unconformity
 A buttress unconformity is when younger is deposited
against older strata thus influencing its bedding
structure.
Y.R.B.
P.O.U.
O.R.B.

14. Signification of Unconformity
 Time interval
 Structural discordance
Topographic relief
 Evidence of weathering at the unconformable surface

15.  Time interval :-
1 – Gap in paleontological record.
2 – Gap in stratigraphic record.

17.  Structural Discordance :- The truncation of
sedimentary layers at the stratigraphic contact is an
unmistakable evidence of discontinuity.

18.  topographic irregularity :- Disconformities preserve
topography corresponding to all stage of the
physiographic cycle ranging from undetected surface
to near pep plains.

19.  Sharp contrast in the degree of indurations between
the underlying and overlying rocks.
 Difference in the grade of regional metamorphism of
the underlying and overlaying rocks.
Presence of basal conglomerate horizon suggest the
existence of an unconformity.

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