THE DARWIN Trail Map provides insights into important natural sites in our city and gives us a sense of how those sites made an impact on him.
One of the places which made a huge impression on him is the Sea Point Contact – a stretch of rock where layers of granite and sedimentary (clay) rock connect.
Before Darwin came along, most people thought rocks were formed under water millions and trillions of years ago. Darwin was intrigued by the rocks at the Sea Point Contact, which look like they have melted into each other and blended.
He thought about the origins of those rocks – and how they got to be like that. To say they had simply got like that under the sea didn't explain why they seemed all mixed up.
He suggested that a “catastrophic geological event” (a volcano, an earthquake?) had shaped the way the rocks fused and made contact with each other. He thought that there may well have been a series of events, so that the formation of rock had built up and evolved over time.