Minnamurra Slot Gorge EarthCache
Hidden : 11/28/2015
Difficulty:
2.5 out of 5
Terrain:
3 out of 5

Size: Size: other (other)

Join now to view geocache location details. It's free!

Watch

How Geocaching Works
Looking for a different adventure?

Please note Use of geocaching.com services is subject to the terms and conditions in our disclaimer.

Geocache Description:


Minnamurra Rainforest Centre in Budderoo National Park features an award-winning visitor centre, a riverside picnic area, and rainforest walks along raised boardwalks. This cache is ONLY accessible during the opening hours, which are 9am–5pm (Closed on Christmas Day). Please note that last access to the cache is 3pm. NPWS entry permit fees also apply (Annual Pass or $12 entry fee).

Source - (visit link)

To reach this Earthcache you will need to walk 1.3km along a boardwalk and paved trail. The return walk is a little shorter. AT NO STAGE ARE YOU PERMITTED TO LEAVE THE MARKED PATH. There is no need to leave the path in order to locate this Earthcache. It is best to expect that there will be no phone reception anywhere near this location.

The location:

The Illawarra Escarpment stretches for around 120 km from the sea cliffs of the Royal National Park in the north to the junction of the Shoalhaven and Kangaroo Rivers in the south. Along its length the Illawarra Escarpment rises from 300m in the north, to 700m in the southern area around Albion Park.

Geological History -The rocks from which the escarpment was carved were originally deposited in an ancient subsidence known as the Sydney Basin. At the close of the Triassic period (about 180-200 million years ago) layers of sedimentary and volcanic rocks in the area began to rise above sea level.

It is interesting to consider the flow patterns of the many streams on the Illawarra plateau. Most of the larger streams follow the fall of the Hawkesbury Sandstone and drain to the inland Nepean River system. These larger streams have a greater impact on the profile of the landscape because of their ability to erode a substantial volume of material resulting in the sizeable river valleys immediately to the west of the escarpment. On the eastern side of the plateau (with the exception of the Macquarie and Minnamurra Rivulets) no river systems have been able to breach the escarpment. This has left the steep vertical cliffs topped by Hawkesbury Sandstone leading to slow erosion along the joint planes.

Extant Geology - The escarpment cliffs and plateau are comprised of massive beds of durable quartz sandstone. Beneath the cliffs, weaker claystone tends to erode more rapidly and undermine the sandstone causing the cliffs to periodically collapse.

Budderoo National Park is part of the Illawarra Escarpment. The highest sections of the park (on the plateau) reach 740m above sea level. They give way to huge sandstone cliffs, 50-100m high, which tower over the rainforests in the lower areas of the park.

In places, streams have cut deep into the cliff lines, forming spectacular waterfalls - including Gerringong Falls and the famous Carrington Falls. Over time, water falling over the Carrington Falls, have cut the deep westward facing valley.

The Minnamurra slot canyon is another product of this weathering. It is a large natural amphitheatre that has been carved out of the Illawarra Escarpment by the Minnamurra River over millions of years.

Another significant site, the famous slot gorge of the lower Minnamurra Falls, is the result of erosion of a volcanic dyke. The slot gorge is approximately 50m long, 50m high and 10m wide. You can see it from the top at the end of the Falls Walk.

Source - (visit link)

To log a find for this Earthcache (optional) take a photo of you &/or your GPS in front of the falls at WP2 and (mandatory) answer the following questions. (Email answers via my www.geocaching.com profile). Please fulfill all requirements of this cache or your log may be deleted.

1. At Waypoint 1 - What process do you think resulted in the the Slot Gorge being formed?
2. At Waypoint 2 - Is the process that formed the Slot Gorge still occurring here? Explain your answer.

Please be careful and remember to not leave the marked track!

I hope you enjoy our first Earthcache.

Additional Hints (No hints available.)



Advertising with Us