A finding of considerable general interest is that not infrequently the horizontal components of the stress field are much higher than can be accounted for by the weight of overburden alone.

In the design of large dams one of the questions the engineer has to consider is what allowance if any should be made to resist earthquake forces. The geologist alone can provide the engineer with only very general and inconclusive evidence bearing on this important question. He can point out that while the Australian continent is regarded as a seismically quiet region on the world scale, it is adjacent to some of the most seismically active regions, in particular to the Southwest Pacific belt from Indonesia and New Guinea to New Zealand.

He can now point to the large Meckering, Western Australia, earthquake of October, 1968, which caused surface faulting over a distance of 17 miles, as an extreme possibility. From a study of structural geology and geomorphology of a region the geologist may be able to reach some conclusions about the occurrence of tectonic activity, but on only the geological time scale. From about 1959 a large expansion of seismograph stations occurred which greatly improved the situation particularly in south-eastern Australia where the majority of large dams is situated.

Here an extensive network of seismographs has been established based on local networks in the Sydney region,

the Snowy Mountains region and Tasmania, set up especially to obtain engineering data.

These stations are designed primarily to record earthquakes of local origin, and to enable their foci and magnitudes to be determined. They have revealed several previously unknown concentrations of minor seismic activity in south- eastern Australia, including one located on the eastern edge of the Snowy Mountains.

A distinctive feature of engineering geology is that it is essentially a service to engineering, and therefore it cannot survive without engineering projects. Geological services to engineering projects are provided by State Geological Surveys, the Bureau of Mineral Resources and consultants, but it is considered that the engineering geologist is most effective as a member of an experienced engineering team. In such a team the engineers become aware and make use of the geo1ogists' specialist knowledge, and the geologists on their part become aware of the geological factors which are significant to particular kinds of projects. They develop specialized skills and equipment and learn to communicate the results to the engineers effectively.

The opportunities to build up and maintain experienced teams in Australia are few, depending on organizations being given responsibility for the construction of a continuing succession of major projects.