This is an EarthCache and has special requirements for logging it. You cannot log a Found It without responding to the logging requirements set out below.
Only one find claim per Message. Each Geocacher claiming a find must submit an individual response. One team can not lodge a response on behalf of a group of people.
An Earth Cache in a Suburban Logan Gorge.
Australia: The Land Where Time Began.
The Silurians are a fictional race of prehistoric and scientifically advanced sentient reptile-like humanoids in the long-running British science fiction television series Doctor Who. They went into self-induced hibernation to survive what they predicted to be a large atmospheric upheaval caused by the Earth capturing the Moon.
On the other hand, the Silurian Period (about 443 to 416 million years ago) was a time when the Earth underwent considerable changes that had important repercussions for the environment and life within it.
In the period of time before the Silurian, there was a great cold ice age. Apparently, it ended abruptly. Then, the continental landmasses were low and sea levels began rising.
According to Wikipedia, The base of the Silurian is set at a major Ordovician-Silurian extinction events when 60% of marine species were wiped out.
Hmmm. The (fictional) Silurains almost got it right!
Here is something else I think is interesting (from the University of California), Although there were no major periods of volcanism during the Silurian, the period is marked by major orogenic [due to the interaction between the earth's tectonic plates] events in eastern North America and in northwestern Europe (the Caledonian Orogeny), resulting in the formation of the mountain chains there. The ocean basins between the regions known as Laurentia (North America and Greenland), Baltica (central and northern Europe and Scandinavia) and Avalonia (western Europe) closed substantially, continuing a geologic trend that had begun much earlier. The modern Philippine Islands were near the Arctic Circle, while Australia [my emphasis] and Scandinavia resided in the tropics; South America and Africa were over the South Pole. While not characterized by dramatic tectonic activity, the Silurian world experienced gradual continental changes that would be the basis for greater global consequences in the future.
Perhaps more of that at another time (or earth cache!).
The basic time line for the Siurian Period was the rise of the oceans (and fish life), the deposition of large sedimentary rockscapes, and then the erosion of such layers which exposed areas of granite.
OK. Now it's What, Where and Why time. Your task here is to walk the loop track (Click here for a guide) and describe where you can find some of these time-line rocks, what they are, and why you think they are there. Then, take of photo of yourself OR your GPS to show a view of the rock(s) you have chosen to describe. Include it in your message, but please do not post it in your log, it might give too much away.
I am NOT interested in the man-made rock-cages near the old quarry.
We often walk the tracks here and are familiar with the area (but we are not great fans of the so-called "Stairs of Death". We normally walk up the gorge, then back down the "stairs" to the car park.) 
Please don't E-mail if possible: MESSAGE the CO via the "Message this owner" link at the top of this page. I don't deal with email very well. 
Emails get lost, and will probably result in your log being removed.
In your MESSAGE, simply describe WHAT rocks you saw and describe WHERE you spied them, and WHY you think they are there.
Please keep it simple, and express your thoughts on this fascinating geological area. In return, I am sure you will enjoy your outing, and, like we did, find this to be another superb hidden suburban gem.