I Read Rocks - Part 1

A special series by Warren Miller

I read rocks! I am pretty average at it. If you were to compare my rock reading abilities to how fast a reader reads a book, I would say I read rocks the same as an average reader reads a book. The thing is – the point of reading (including rocks for this matter) is not to get to the last page of the book as fast as possible, but to rather enjoy the read. Take it step by step, enjoying the unfolding story and if necessary go back a few pages from time to time when things aren’t making sense.  

I have spent the past few years trying to understand a certain grouping of rocks that are rather old and severely deformed. These rocks I speak of outcrop near my home town of Port Elizabeth, along the striking coast between Sardinia Bay and Kini Bay (see below). 

Overview of the study area being investigated, highlighted in red

Similar aged rocks have also been studied in various other parts of the southern tip of Africa, including Damaraland, Cape Nollath, Cape Town, Oudtshroon and George. I have made a pretty picture to help you see the broader setting of southern African geology over the past 1000 – 200 Ma.

This is called a stratigraphic column. It is based on the principle of superposition: that is to say if a sequence of rocks are positioned below another sequence of rocks, the former sequence is older than the latter – assuming there has been no tectonic disruption or the tectonic disruption is resolvable. So look at my picture, enjoy it. I like to draw as I read. It makes the reading more fun.

Now back to my rocks. For months and months I hadn’t a clue what I was reading. Rocks were all over the place. I couldn’t piece the sentences together. It was a mess. It was like a riddle that kept banging against my head week in and week out. But luckily I have some friends who also enjoy reading rocks, of which some of them are a lot better than me. So I would bring them along and we would read together and discuss our interpretations over a big glass of black label beer often making very little progress. But after some time and a little help from another friend in Australia and a very hi-tech machine I was able to make some very interesting progress.

To be Continued…

Warren Miller is a Masters of Geology student at the Nelson Mandela Metropolitan University (NMMU), working within the Africa Earth Observatory Network (AEON) and Earth Stewardship Science Research Institute (ESSRI). He is currently finishing his thesis, looking into the structural dynamics effecting the rocks along the southeast coast of South Africa. Here, he will take us on a journey into the mind of Geologist, listening and observing carefully to the Earth’s Story as it unfolds layer, by layer. As you can see, this is a complex story!