Geologists Harris and Gass hypothesized that the Red

Sea rift developed along the line of a suture (a splice in the

Earth’s crust) formed during the late Proterozoic era, and

that significant observable differences in the composition of

(5)the upper layers of rocks deposited on either side of the

suture give clues to the different natures of the underlying

igneous rocks.

Other geologists argued that neither the upper rock layer

nor the underlying igneous rocks on the one side of the rift

(10)differ fundamentally from the corresponding layers on the

other side. These geologists believe, therefore, that there is

inadequate evidence to conclude that a suture underlies the

rift.

In response, Harris and Gass asserted that the upper rock

(15)layers on the two sides of the rift had not been shown to be

of similar age, structure, or geochemical content. Further-

more, they cited new evidence that the underlying igneous

rocks on either side of the rift contain significantly different

kinds of rare metals.

Part of the Harris and Gass hypothesis about the Red

Sea rift would be weakened if it could be demonstrated

that the composition of upper rock layers

(A) cannot cause a suture to develop

(B) has no effect on where a suture will occur

(C) cannot provide information about the nature of

underlying rocks

(D) is similar on the two sides of a rift unless a suture

divides the two sides

(E) is usually different from the composition of

underlying rocks

It can be inferred from the passage that the "Other

geologists" (line 8) would be most likely to agree with

which of the following statements?

(A) Similar geological features along both sides of a

possible suture imply the existence of that suture

(B) Sutures can be discovered only where they are not

obscured by superimposed geological features.

(C) The composition of igneous rocks permits pre-

diction of the likelihood of a rift developing

through them.

(D) It is possible to date igneous rocks by carefully

studying the different kinds of rare metals

contained in them and by observing their simi-

larity to the layer of rock that lies above them.

(E) The existence of rock layers on one side of a rift

that are similar in composition to rock layers on

the other side suggests that no suture exists

between the two sides.