Form of weathering caused by the activities of living organisms for example, the growth of roots or the burrowing of animals. Tree roots are probably the most significant agents of biological weathering as they are capable of prising apart rocks by growing into cracks and joints. Plants also give off organic acids that help to break down rocks chemically (see chemical weathering).
White stands for peace. The shield and weapons express a willingness to defend the country. Green symbolizes plenty. Blue represents rain. Effective date: 20 January 1987.