<strong>Introduction:</strong>In prehistoric humans, when the jaw size permitted space for normal dental development and position in the arches, third molar may have been a vital survival tool. However, as human evolution has progressed, jaw size has been gradually decreasing (Lamarckian Evolution). Hence due to the decrease in size of the jaw bone, it’s been reported that approximately 65% of the human population has at least one impacted third molar, and third molars that do erupt are often malposed in the arches and are consequently difficult to clean and prone for infection.<p><strong>Aim and Objective:</strong> To study the prevalence of eruption of third molar tooth among South Indians and Malaysians by observing the presence of third molars among them and to analyze the percentage of impacted third molars and congenital absence of third molar teeth among the Indian and Malaysian population.</p><p><strong>Materials and Methods:</strong>50 Malaysians and 50 Indians (25 males and 25 females in each population) aged between 17 to 25 years old were examined for the presence or absence of the third molars. To confirm the congenital absence of third molars, Orthopantomograms (OPG) were taken.</p><p> </p><p><strong>Results and Conclusion:</strong> In South Indian Population, it was noted that only 48% of males and 64% of females have congenital absence of third molar, and 52% of males and 36% of females have erupted third molars. 16% of males had partly impacted third molar whereas in case of female it was 28%. Congenital absence of third molars among females was 16% more than in males. More males (36%) had impacted third molars than females (24%). It was also noted that majority of them have their maxillary third molars erupted first before their mandibular third molars. In Malaysian Population, it was noted that only 28% of males and 20% of females had congenital absence of third molars, and 72% of males and 80% of females had erupted third molars. 40% of males had partly impacted third molar whereas in case of female it was 52%. Congenital absence of third molars among males was 8% more than females. More males (32%) had impacted third molars than females (28%). It was also noted that in majority of them their mandibular third molars had erupted before their maxillary third molars. When compared among south Indians and Malaysian population congenital absence and impacted third molars are more common in south Indians, whereas partly impacted third molar is more common among Malaysians.</p>

The anisotropy of magnetic susceptibility (AMS) study was performed on soft sediment samples from a trenched fault zone across the Himalayan frontal thrust (HFT), western Himalaya. AMS orientation of K min axes in the trench sediments is consistent with lateral shortening revealed by geometry of deformed regional structures and recent earthquakes. Well-defined vertical magnetic foliation parallel to the flexure cleavage in which a vertical magnetic lineation is developed, high anisotropy, and triaxial ellipsoids suggest large overprinting of earthquake-related fabrics. The AMS data suggest a gradual variation from layer parallel shortening (LPS) at a distance from the fault trace to a simple shear fabric close to the fault trace. An abrupt change in the shortening direction (K min ) from NE-SW to E-W suggests a juxtaposition of pre-existing layer parallel shortening fabric, and bendingrelated flexure associated with an earthquake. Hence the orientation pattern of magnetic susceptibility axes helps in identifying co-seismic structures in Late Holocene surface sediments.

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