Many theorists now doubt that heat loss from Earth’s core and radioactive decay are sufficient by themselves to produce all the energy driving the tectonic plates whose movements have helped shaped Earth’s surface. This leaves a loose end in current geological theory. Herbert Shaw argues that because scientists have underestimated the input of substantial amounts of energy from extraterrestrial impactors (asteroids and comets striking Earth), they have difficulty accounting for the difference between the quantity of energy produced from sources intrinsic to Earth and that involved in plate tectonics. Whereas most geologists have treated the addition of energy through the bombardment of Earth’s surface by such impactors as a process separate and independent from the movement of Earth’s tectonic plates, Shaw asserts that these processes are indivisible. Shaw’s revolutionary “open-system” view recognizes a continuum between terrestrial and extraterrestrial dynamics, whereas modern plate tectonic theory, like the classical geology developed during the nineteenth century, is founded on the view that Earth’s geological features have changed through gradual, regular processes intrinsic to Earth, without reference to unique catastrophic events. Classical geology borrowed a decisive, if unspoken, premise from Newton—the independence of Earth’s processes from any astronomical context.

  1. The author’s primary purpose is to

  A. identify the influences informing a particular geological theory about the processes that have shaped Earth’s surface

  B. identify differences between two views of the extraterrestrial impactors and argues that the phenomenon has influenced the development of plate tectonic theory

  C. argue that an explanation is based on a dubious evidence and propose an alternative explanation

  D. discuss an explanation and place that explanation under theoretical context

  E. suggest that apparent discrepancy poses a serious problem for a particular theory that many have believed

  2. The author of the passage mentions the “continuum” in order to

  A. point out a relationship between plate tectonics and the nineteenth-century geology

  B. explain how a theory of Newton’s could influence geology and plate tectonic theory.

  C. distinguish between two sources of energy that contributed to the development of Earth’s surface.

  D. point out a similarity between the surface of impactors and the surface of Earth.

  E. identify a feature of Shaw’s view that deviates from current scientific theories.

  3. The passage suggests which of the following about tectonic theory?

  A. It has led scientists to overlook an important contribution to classical geologists from Newton.

  B. It has been more successful than was classical geology in accounting for heat loss from.

  C. It is based on premise about Earth’s processes discerned in Newton’s thought.

  D. It has correctly explained the effects of extraterrestrial impactors on Earth’s surface.

  E. It corrects a fundamental flaw in classical geology.