Prior to 1965 geologists assumed that the two giant rock plates meeting at the San Andreas Fault generate heat through friction as they grind past each other, but in 1965 Henyey found that temperatures in drill holes near the fault were not as elevated as had been expected. Some geologists wondered whether the absence of friction-generated heat could be explained by the kinds of rock composing the fault. Geologists pre-1965 assumptions concerning heat generated in the fault were based on calculations about common varieties of rocks, such as limestone and granite; but weaker materials, such as clays, had already been identified in samples retrieved from the fault zone. Under normal conditions, rocks composed of clay produce far less friction than do other rock types.

In 1992 Byerlee tested whether these materials would produce friction 10 to 15 kilometers below the Earths surface. Byerlee found that when clay samples were subjected to the thousands of atmospheres of pressure they would encounter deep inside the Earth, they produced as much friction as was produced by other rock types. The harder rocks push against each other, the hotter they become; in other words, pressure itself, not only the rocks properties, affects frictional heating. Geologists therefore wondered whether the friction between the plates was being reduced by pockets of pressurized water within the fault that push the plates away from each other

1. The passage suggests which of the following regarding Henyeys findings about temperature in the San Andreas Fault?

A. Scientists have yet to formulate a definitive explanation for Henyeys findings.
B. Recent research suggests that Henyeys explanation for the findings should be modified.
C. Henyeys findings had to be recalculated in light of Byerlees 1992 experiment.
D. Henyeys findings provided support for an assumption long held by geologists.
E. Scientists have been unable to duplicate Henyeys findings using more recent experimental methods.

OA: A

2. The passage is primarily concerned with

A. evaluating a method used to test a particular scientific hypothesis
B. discussing explanations for an unexpected scientific finding 
C. examining the assumptions underlying a particular experiment
D. questioning the validity of a scientific finding
E. presenting evidence to support a recent scientific hypothesis

OA: B

At the beginning:

Prior to 1965 geologists assumed that the two giant rock plates meeting at the San Andreas Fault generate heat through friction as they grind past each other, but in 1965 Henyey found that temperatures in drill holes near the fault were not as elevated as had been expected.

^^ "Not as _____ as expected" is the same as "unexpected". So there's your unexpected finding.

The entire rest of the passage is dedicated to hypotheses and/or research aimed at explaining what Henyey found.

3. The passage mostly agree that Henyeys findings about temperature in the San Andreas Fault made the greatest contribution in that they

A. revealed an error in previous measurements of temperature in the San Andreas Fault zone
B. indicated the types of clay present in the rocks that form the San Andreas Fault
C. established the superiority of a particular technique for evaluating data concerning friction in the San Andreas Fault
D. suggested that geologists had inaccurately assumed that giant rock plates that meet at the San Andreas Fault generate heat through friction
E. confirmed geologists assumptions about the amount of friction generated by common varieties of rocks, such as limestone and granite

OA: D

As usual, trying to read too many words here is a bad thing. The whole passage is about Henyey's findings, so, to get a sense of their significance, we just need to read the part that introduces them:
Prior to 1965 geologists assumed that the two giant rock plates meeting at the San Andreas Fault generate heat through friction as they grind past each other, but in 1965 Henyey found

That's all we need; this introduction only makes sense if Henyey found something that contradicted that assumption.

Detailed Analysis By STACEY KOPRINCE

http://www.beatthegmat.com/mba/2016/11/26/gmatprep-reading-comp-tackling-a-science-passage-part-1

http://www.beatthegmat.com/mba/2016/12/04/gmatprep-reading-comp-tackling-a-science-passage-part-2

http://www.beatthegmat.com/mba/2016/12/05/gmatprep-reading-comp-tackling-a-science-passage-part-3