Welcome to Tin City, Stockton Beach.

This Earthcache will have you visit Tin City, a set of 11 mysterious corrugated metal settlements hidden amongst endless sand dunes. 

This Earthcache will teach you about sand dune dynamics, wind-driven formations, and the impact of structures like Tin City on the natural movement of sand.

Trust me, it is something straight out of Star Wars.

Tin City History

In the late 19th century shipwrecks on Stockton Beach were so common that two tin sheds were constructed on a part of the beach in what is now Bobs Farm near Salt Ash to hold provisions for shipwrecked sailors. Then it was built up as a camp by a community of homeless men in the late 1920’s during the Great Depression. In the 1930s it grew out to around 36 huts, and today 11 shacks still stand, many being torn down for an army camp in WWII.

Today, the shacks are governed by a one hundred year lease signed in 1920 under longstanding squatters settlement. The shacks are not owned but are privately occupied and passed down to family and friends. No new shacks can be erected, nor can they be rebuilt if they are destroyed to the elements.

The shacks may be occupied when you visit. When we visited, two cars were parked outside some of the huts. Please exercise caution, and do not get too close to any of the properties. Remember, you are in the middle of nowhere!

Location 

Stockton Beach is located in Worimi National Park, owned and co-managed by the local Worimi Aboriginal community in partnership with NSW National Parks. The Stockton Bight landscape is home to an extraordinary number of ancient cultural sites.

Stockton Beach is a 32 kilometer long beach, and holds the largest moving sand dunes in the Southern Hemisphere, moving around 4m every year. Some of the dunes are up to 30 meters tall which appear mountain-like in person. 

Stockton Beach is highly popular with 4WD enthusiasts, as you can travel almost its whole length by car, watching the waves, beach fishing, and even camping in one area.

Along Stockton Beach, also checkout the shipwreck MV Sygna! (See WPs). 

Access

I would recommend attempting this Earthcache via a 4WD. Other possible methods include walking along Boyce's Trail (6km round trip from WP), cycling (sounds awful on sand) or renting a quadbike!

Stockton Beach requires a paid permit of $33 for a 3-Day Pass or $88 for a Year Pass for cars. You can buy a permit from the Port Stephens Visitor Information Centre, BP Service Station (Anna Bay), BP Service Station (Salt Ash), or Pearl Energy Service Station (Williamtown). You must display the permit on the lower left side of your vehicle's windscreen or another prominent position. 

Walkers, bike riders, and horse riders can enter for free. If walking / riding, consider Boyce's Trail in WPs

For 4WD, entry to Stockton Beach is via 3 entry points (in Waypoints). The best entry for this Earthcache is Lavis Lane, Williamtown as it is the closest and widest. The second best entry would be Gan Gan Entry, Anna Bay at the North of the beach, and you can also access at Fern Bay Entry at the South side of the beach.

Note: When 4WD, it is recommended to reduce your tire pressure to ~20 psi to allow for greater surface area of the wheels, and to have a lighter load. You can refill your tires at Williamtown Service Station or Anna Bay BP which are close to the entry points.

Note: You are not allowed to drive behind/on the sand dunes, and are meant to stay along the beachfront (with the exception of the entry points and Tin City parking).

Earthcache Lesson - Aeolian Transport, Ripples and Dunes

Sand Movement

The sand dunes in this part of the beach are a testament to the forces of wind moving sand through aeolian transport. There are three key transport mechanisms. 

• Saltation: Sand grains are picked up by the wind and hop across the surface. About 75% of sand movement is achieved through saltation.

• Creep: Larger grains are rolled along the ground by wind.

• Suspension: Fine particles are lifted and carried over long distances.

Ripple Formation

Sand Dunes display ripple formations along their surfaces which seem like unlikely order out of chaos. The reason these ripples form is that as sand moves through saltation, bouncing along the surface, a lump can form when the wind deposits a greater amount of sand in a particular location. This can happen due to similar grain sizes moving similar distances. As a lump is formed it causes more sand to land there, and it leaves a shadow behind it where less sand is deposited due to coinciding with the growing lump first. Thus a ripple shape is formed. 

When there is unidirectional wind, the ripples that form will be asymmetrical. The side facing the oncoming wind tends to be smoother and is called the stoss side. Here wind is accelerated up the ripple, taking sand from the front and depositing it at the crest, allowing the ripple to grow. However once the ripple reaches a critical angle of 33-34°, the ripple can no longer hold its shape and there is an 'avalanche' on the lee side. This forms a sharper side behind the ripple.

More complex ripple patterns are formed when wind currents are non-uniform, or if the wind direction changes. Symmetrical ripples tend to be formed when there is bidirectional wind/forces, aka wind moving in both directions, causing the ripple to even out. Additionally, ripples tend to be made from medium to coarse sand, and finer sand typically forms smooth surfaces. 

This movement of sand forming ripples also happens on different scales. When the size of the sand build up is:

• <5cm it is called a ripple mark
• 5-10cm it is called a megaripple
• >10cm it is called a dune

Hence, sand dunes are pretty much formed from the same process, just at a larger scale!

Interaction with Obstacles

Sand Dunes often start when sand is deposited on and around obstacles on a beach. Driftwood, rocks and vegetation can all act as windbreaks for sand to be deposited around, and a small lump is formed. As the lump expands, it grows into an embryo dune, the earliest stage of the dune lifecycle. 

When there are large structures, such as buildings, sand dunes form unique structures around them. This is due to them acting as windbreaks, but also changing the direction of wind currents from the natural course. 

On the windward side, sand is pushed against the side of a building facing the wind. The kind of dune formed depends on the angle of the obstacle. If the angle of the obstacle is greater than approximately 55°, then an eddy current forms when strong winds persist (seen in diagram), which prevents sand from building up directly on the obstacle, but rather slightly away from it. This is called an echo dune. If the slope is less than 55°, then the eddy is either small or non-existant, allowing a climbing dune to form, which sits right on the obstacle.

On the leeward side, if the lee slope is steeper than the windward slope, a falling dune can form. Additionally, structures influence wind currents, and wind can be swirled around structures which causes erosion. It is also common for sand moving in suspensions to settle if the structure forms a windbreak, creating a smooth, ripple-less surface.

Logging Requirements

In order to log this cache, you must submit answers to the CO via the message center or email. The purpose of the logging tasks is to demonstrate what you have learnt from the Earthcache lesson. 

NOTE: The posted coordinates take you to the edge of the carpark at Tin City. From here, you need to venture inwards into the city.

1. Take a photo [REQUIRED] in front of Tin City. You can either pick your favourite building, or go for a more artistic wide shot of the whole city. You can either show yourself, or an item that identifies you as a Geocacher (Username, GPS, Badge). Upload this photo to your log.

2. Look closely at your feet as you walk around Tin City and observe the ripples in the sand. Estimate the distance between ripples, their size (ripplemarks or megaripples), and determine the direction the wind has been flowing. Observe whether the ripples are symmetrical or asymmetrical.

3. Walk around Tin City and observe how the sand has built up around one building. Find examples of at least 2 out of: 

• climbing dunes
• echo dunes 
• eroded dunes due to swirling winds on leeward side

Take photos of these features and send them to me, and explain how they might have formed. 

4. Tin City is slowly being swallowed by the sand. Find an example of the sand 'burying' the houses, such as sand on the roof. Take a photo and send it to me, and explain which aeloian transport method likely led to it getting there.

This geocache was part of GC Project: It's Raining Caches 2025.  

The project's aim was to create a rain of new geocaches to fall from the sky across the state of NSW at 9am on 19th January 2025 - 1 week before Sydney Geoquest, the first Block Party in the Southern Hemisphere.

Many legendary hiders came together to generously contribute their finest geocaches to build excitement and connection amongst the community and for all finders to enjoy years after the event. 

This geocache helped make it rain.