Dalton has long attracted the attention of geologists. Back in the late 1800s it was a thriving gold mining town, with reports that in 1879 ore crushing batteries were operating 24 hours a day. The town is also famous for experiencing regular earth tremors as it is situated on a geologically active fault in the earth's crust.
Here in this little park you can see a preserved slab of local stone containing many finely detailed leaf fossils. Some 21 million years ago a flow of basalt lava dammed the Lachlan River near the Jerrawa Creek junction. This resulted in a lake which extended back over the location of present-day Dalton. At the time the climate was much wetter and the area was covered in thick forest similar to that around the Minnamurra Falls in the Illawarra. Leaves from this forest fell into the lake water and were buried in the sediment. Over time the sediment was hardened into a pebbled silcrete and the leaves became preserved as fossils. The Lachlan River eventually partly eroded the basalt away, the lake drained and the fossils were left exposed in a small outcrop.
To log this Earthcache:
Visit GZ and examine the large rock in the shelter, and the nearby information board. Message me your answers to the following:
1. Examine the stone and describe what you see. How does the colour and texture of the fossilised leaves compare to that of the surrounding rock?
2. When the sediment hardened, what kind of stone was formed?
3. Originally these fossils were thought to be about 40M years old. That was revised to 21M after studying what type of stone, which had caused the formation of the lake and thus the fossils?
4. Please include a photo of yourself, your GPS or some personal item at GZ, as proof of your visit. But please don't include any spoilers or answers to the questions in your photo.
You may post your Found log immediately without waiting for my response. If I don't receive correct answers within 7 days of your Found log being posted, I may delete your log. Please don't post answers to the questions above in your log.