Answer:
Option (3)
Explanation:
Unconformity is defined as the gaps in the sequence of geological rocks. It is a geological contact that marks the boundary between the different types of rocks. In simple words, they are also known as the time of non-deposition. These unconformities have great significance in the field of geology. They are of 4 types, namely-
(1) Angular unconformity- The sedimentary rocks are initially formed and deposited in an area, after that the area is tilted and erosion takes place. Now, the new sediments are deposited forming an angle, which is commonly known as an angular unconformity.
(2) Non-conformity- When the sedimentary rocks are deposited over the igneous or metamorphic rocks, then it is known as the non-conformity.
(3) Para conformity- When the sedimentary rocks are deposited parallel to the ground surface, and absence of erosion activity, then these surface appears to be a normal (simple) bedding plane. This is known as the para conformity.
(4) Disconformity- When the sedimentary rocks are formed and undergoes erosion, then new sedimentary rocks are deposited over this and diminishes the unconformity. This forms a discontinuity.
Thus, the unconformity arises due to both erosion and lack of rock deposition.
Hence, the correct answer is option (3).
