101. Self-perception of heightened arousal then leads to heightened emotional activity. Other links may involve changes in brain temperature and the release of neurotransmitters (substances that transmit nerve impulses.)
102. Ekman has found that the so-called Duchenne smile, which is characterized by ''crow’s feet" wrinkles around the eyes and a subtle drop in the eye cover fold so that the skin above the eye moves down slightly toward the eyeball, can lead to pleasant feelings
103. Ekman’s observation may be relevant to the British expression “keep a stiff upper lip” as a recommendation for handling stress. It might be that a “stiff” lip suppresses emotional response -- as long as the lip is not quivering with fear or tension.
104. Hills and mountains are often regarded as the epitome of permanence, successfully resisting the destructive forces of nature, but in fact they tend to be relatively short-lived in geological terms.
105. Lower mountains tend to be older, and are often the eroded relics of much higher mountain chains.
106. Some mountains were formed as a result of these plates crashing into each other and forcing up the rock at the plate margins.
107. Other mountains may be raised by earthquakes, which fracture the Earth's crust and can displace enough rock to produce Block Mountains.
108. The exposed rocks are attacked by the various weather processes and gradually broken down into fragments, which are then carried away and later deposited as sediments.
109. Rain washes away loose soil and penetrates cracks in the rocks.
110. Glaciers may form in permanently cold areas, and these slowly moving masses of ice cut out valleys, carrying with them huge quantities of eroded rock debris.
