Years before the advent of plate

       tectonics―the widely accepted theory,

       developed in the mid-1960’s, the holds

Line that the major features of Earth’s surface

  (5)       are created by the horizontal motions

of Earth’s outer shell, or lithosphere―

a similar theory was rejected by the

geological community.  In 1912, Alfred

Wegener proposed, in a widely debated

(10)       theory that came to be called continental

drift, that Earth’s continents were mobile.

To most geologists today, Wegener’s

The origin of Continents and Oceans

appears an impressive and prescient

(15)       document, containing several of the

essential presumptions underlying plate

tectonics theory: the horizontal mobility

of pieces of Earth’s crust; the essential

difference between oceanic and conti-

(20)       nental crust; and a causal connection

       between horizontal displacements and

       the formation of mountain chains.  Yet

despite the considerable overlap

between Wegener’s concepts and the

(25)       later widely embraced plate tectonics

theory, and despite the fact that conti-

nental drift theory presented a possible

solution to the problem of the origin of

mountains at a time when existing expla-

(30)       nations were seriously in doubt, in its

day Wegener’s theory was rejected

by the vast majority of geologists.

             Most geologists and many historians

today believe that Wegener’s theory

(35)      was rejected because of its lack of an

adequate mechanical basis.  Stephen

Jay Gould, for example, argues that

continental drift theory was rejected

because it did not explain how continents

(40)       could move through an apparently solid

oceanic floor.  However, as Anthony

Hallam has pointed out, many scientific

phenomena, such as the ice ages, have

been accepted before they could be fully

(45)       explained.  The most likely cause for the

rejection of continental drift―a cause

that has been largely ignored because

we consider Wegener’s theory to have

been validated by the theory of plate

(50)       tectonics―is the nature of the evidence

that was put forward to support it.  Most

of Wegener’s evidence consisted of

homologies—similarities of patterns and

forms based on direct observations of

(55)       rocks in the field, supported by the use

of hammers, hand lenses, and field note-

books.  In contrast, the data supporting

plate tectonics were impressively

geophysical—instrumental determinations

(60)       of the physical properties of Earth gar-

nered through the use of seismographs,

magnetometers, and computers.

Q27:

It can be inferred from the passage that geologists today would be most likely to agree with which of the following statements about Wegener’s The Origin of Continents and Oceans?