Question

Which type of sandstone is more stable?

(a) Cemented with siliceous material

(b) Cemented with argillaceous material

(c) Cemented with ferruginous material

(d) Cemented with calcareous material

This question was posed to me in an international level competition.

This interesting question is from Causes of Mass Movements topic in portion Mass Movements of Engineering Geology

Answer 1

Correct answer is (a) Cemented with siliceous material

The explanation is: Sandstones for instance, occur in a great variety of types. Fine textured, dense and massive sandstones with siliceous cements may be very stable even at vertical slopes whereas the same rock with ferruginous, calcareous and clayey cements may become unstable at angle of 60° or even less.