🪨 Ryde Rocks! [Ryde] EarthCache

🛰 Ryde Rocks!
Ryde District Quarries [Ryde] 🌏

This multi-site EarthCache will take you on a short journey of geological discovery around a significant, yet relatively unknown, part of the City of Ryde's history.

Acknowledgement of Country

As the Cache Owner, I wish to acknowledge the Traditional Custodians of the Land on which this cache is located, the Wallamattagal People of the Darug Nation, and their continuing connection to Country and community; and pay my respect to Elders past and present.

Their land stretches from the north shore of the Parramatta River, including the City of Ryde, from the intersection of the Lane Cove River and west to Parramatta.

I recognise the Aboriginal and Torres Strait Islander people as the First Australians and am committed to honouring their unique cultural and spiritual relationships to the land, waters and seas, and their rich contribution to society.

Are you a CITO Crusader?

Every geocache presents us with a perfect opportunity to CITO (Cache In Trash Out).

Please help clean up some litter while you're here visiting this cache and attach a photo to your log to show off your much appreciated efforts!

Finding this Geocache

Instructions and How to Verify Your Find

Once you have visited all Waypoints and complete the EarthCache requirements you can post your find, as per the EarthCache guidelines.

You will, however, need to verify your Find by sending me a message via the Message Center with the GC code and cache name (GC45211 Ryde District Quarries) on the first line and provide your answers to the questions listed below, otherwise your log may be removed. To do this, visit my profile and click on Send Message.

Adhering to the EarthCache guidelines, please be careful not to include any detail in your log or photos that may assist others in answering the questions without actually visiting the sites and carrying out the fieldwork.

Make sure you stick to the paths and leave no trace. Watch out for traffic when crossing the roads as you move between the waypoints. Please do not damage the geological material, vegetation or wildlife – the tasks can be completed without the need to disturb the environment.

OPTIONAL: Take a photo of yourself, as well as any other members of your party, with GPS in hand at GZ (S 33° 48.430 E 151° 07.180) and ensure the terraces are clearly visible in the background. When you reach waypoint Q5 (S 33° 48.855 E 151° 07.330), take another photo like the one above but with the site of the old Cressy Road Quarry in the background (i.e. the hill leading up to Pidding Park & the cemetery). Upload both photos to your log.

EarthCache Questions:

1) Find the 'desire path' at waypoint Q1 (S 33° 48.280 E 151° 07.151) to name the type of rock that is exposed around the top of the terraces and explain the reasoning behind your answer. Also, mention any other material you spot in among the rocks.

2) Proceed to waypoint Q2 (S 33° 48.573 E 151° 07.205), name the geological material used to hold up this structure, and describe its look and feel.

3) Detail the process that is occurring in the top ~20cm of the soil at waypoint Q3 (S 33° 48.676 E 151° 07.272) and what is causing it to happen.

4) Name the feature at waypoint Q4 (S 33° 48.728 E 151° 07.293), describe what it was used for and the material it is made from.

5) Southwest of waypoint Q5 (S 33° 48.855 E 151° 07.330), towards the roundabout at the intersection of Pidding Road, Cressy Road & Robinson Street, there is a bridge crossing Buffalo Creek. What material is the bridge made from, what year was it constructed and how does the material differ from the feature mentioned in question 2? Give an educated guess as to what has caused this difference.

FTF honours: bella at waggy.

Earth Sciences Lesson: Geological Material

The Lane Cove Valley features three main types of naturally occurring geological landforms: Hawkesbury Sandstone, Mittagong Formation and Ashfield Shale.

Hawkesbury Sandstone is predominately made up of coarse-grained sand (mainly quartz grains) but with variable amounts of claystone grains. A large a powerful river deposited its flood plain of sandbars, lagoons and braided channels to form the Hawkesbury Sandstone around 235 to 240 million years ago. Over time the sand settled, was buried and then cemented into rock by iron carbonate deposited between the grains. The iron content is responsible for the ochreous, or rusty stains and bands, which gives the Hawkesbury Sandstone its distinctive yellow-brown colouring.

Mittagong Formation is a thin, transitional unit that gradationally overlays the Hawkesbury Sandstone and consists of thinly bedded sandstone, siltstone and claystone. Usually less than 6m in thickness, it is only found in certain parts of the Lane Cove Valley. Mittagong Formation is identified by its thin, reddish-brown to yellowish-brown gritty clay soil with scattered laterite nodules and fragments of lateralised siltstone and sandstone.

Ashfield Shale overlies the Mittagong Formation, where present, or the Hawkesbury Sandstone and dates back to 235 million years ago. It is a mixture of claystone, laminate, siltstone and thin sandstone deposited in shallow coastal lagoons and swamps that were crossed by meandering streams. Ashfield Shale is dark grey to black in colour due to the minor organic matter and a high content of siderite (iron carbonate mineral) and is more brittle than Hawkesbury Sandstone.

Soils are a by-product of the bedrock and form as a result of chemical and physical weathering, creating new minerals such as clays. Rain and water runoff move the surface matter and slowly filter the finer particles away from the coarser sandy particles. The soil is naturally turned over by a remarkable amount of biological activity, including earthworms, ants, terminates and other invertebrates. These creatures create and consume organic matter and act to mix the surface soil. Depending on the type of bedrock near the surface, the soil that is produced will have varying levels of fertility and chemical properties, which will directly influence the types of vegetation that will be able to grow in the area.

(Sources & further reading:
Thank you to both Simon Mould (Leaves and Sticks) and John Byrnes (Geo-Sites) for sharing their expertise on the geological aspects of this EarthCache, as well as to expand my knowledge and appreciation of this science.
Also, thank you to Margaret Farlow & Betty Willis (Ryde District Historical Society) for providing the background information on the Marsfield Tile, Brick & Pottery Works.
Other sources included the Field Guide to the Bushland of the Lane Cove Valley by John Martyn (STEP Inc), and Geology.com).

Overview of the Waypoints

Starting Co-ordinates:

You are standing on the site of the former Marsfield Brick, Tile, and Pottery Works, Ltd, which was owned by Whitmore & Gardiner. Information on this site is not readily available but it is believed that operations began in the early 1900’s (maybe earlier) and ceased in the late 1970’s or early 1980’s, at which time the land was subdivided and converted into today’s Gannan Park.

Waypoint 1: Q1

This area was part of the quarry adjacent to the Marsfield Brick, Tile & Pottery Works.

Waypoint 2: Q2

This area is the site of another quarry and the disused thoroughfare over Buffalo Creek.

Waypoint 3: Q3

This section borders on residential land and connects Pidding Park down to Pidding Road. Steer clear of the private properties when answering question 3.

Waypoint 4: Q4

A hidden (but not forgotten) reminder of yesteryear.

Waypoint 5: Q5

Site of the former Cressy Road Quarry, now known as Pidding Park. There is also an entrance to the Field of Mars Reserve to the East and the pathway up the hill will take you towards the Field of Mars Cemetery.

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