A motor unit is made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron's axonal terminals.roups of motor units often work together to coordinate the contractions of a single muscle; all of the motor units within a muscle are considered a motor pool. All muscle fibers in a motor unit are of the same fiber type.
SURFACE STRUCTURE. Basaltic lava flows erupt primarily from shield volcanoes, fissure systems, scoria cones, and spatter cones. These fluid lava flows can be subdivided into two end-member structural types, based primarily on the nature of lava flow surfaces: 1  Pahoehoe Lava -- Surfaces are smooth, billowy, or ropy.
The Auckland volcanic field has erupted this type of hot, runny iron-rich lava, and the landscape is dotted with mountains made from basalt and scoria (a red-coloured rock that contains large amounts of iron-rich minerals).Both rock types are excavated for building materials and landscaping.nce the lava has erupted, it cools and solidifies into rock: 1  Basalt magma often forms shield volcanoes. 2  Andesite magma often forms cone volcanoes. 3  Rhyolite magma often forms calderas. 4  Depending on how much gas the magma contains, it can also form cone volcanoes.