Warrnambool sits on rocks built up over the last million years or so - a very short time in geological terms. A marine embayment has slowly infilled. As it did so the region has been rocked by earthquakes and volcanic eruptions. This earthcache will examine wind blown sandstone features.
Sedimentary rocks contain features that show the processes and conditions of deposition. One feature is cross bedding, which is layering within strata and at an angle to the main bedding plane. The direction of motion of the cross-beds can show ancient flow or wind directions (called paleocurrents). The orientation of the cross-beds therefore indicates the direction of the paleocurrents.
In an aeolian environment, cross beds can exhibit inverse grading due to their deposition by grain flows. Winds blow sediment along the ground until they start to accumulate. The side that the accumulation occurs on is called the windward side. As accumulation continues to build, some sediment falls over the end. This side is called the leeward side. As more sediment piles on top the weight causes the underlying sediment to cement together and form cross beds.
Examine the exposed rocks in the cutting at the listed coordinates. Can you see evidence of layers within the strata. This is cross bedding. Please send your answers for the following earthscience tasks to the cache owner by message or email. Find can be logged immediately, but the log may be deleted if the answers are not sent within 14 days.
1.What is the apparent direction of the cross bedding?
2.Does the angle of the cross bedding change?
3.Estimate the thickness of the cross bedding layers?