Geography
The Garden's site allows for different planting conditions. Its altitude ranges from 10 metres at the lowest point of Deep Creek to about 60 metres in the south-west corner next to the Princes Highway.
The topography of the site is gently undulating with slopes of about 1:15. Slopes are locally steeper, especially along the creek.
How it all began
More than 400 million years ago, two plates of the earth’s crust were colliding at the Garden's site. It would have been an earthquake zone as active as any in the world today.
The rocks within the Garden are part of a sequence of sandstone, siltstone and shale. These are possibly many thousands of metres thick, and geologists call them 'the Adaminaby Group'. The rocks extend from the coast to the Snowy Mountains area. These sediments occurred over 30 million years.
You can see the extent of plate movement in some of the rocks that occur in an area from Batemans Bay, south-east, to Burrewarra Point, east of the Garden site. They are well exposed along the coastal cliffs.
The sedimentary nature of rocks in the area provides the Garden with many different soil types. These include siltstone, claystone, sandstone, quartzite, and chert.
You can find the best rock exposures in the steep slopes of the west side of Deep Creek, in the northern quarter of the Garden. These rocks include the full range of sediments typical of the Adaminaby Group. They also include a vein of quartz created during burial and compression of the sediments.
Rock exposures within the Garden show no significant rock types.
Over much of the Garden site, the soil is skeletal grey loam - one to five centimetres deep - over gravelly clay. Nutrient-poor soil created from sandstone is evident in some areas. On steeper slopes - in the south-west of the Garden - areas of stripped soil and gravel patches are common. Next to the major creek lines, deeper loam soil supports a rich flora dominated by large trees.
We carried out a soil analysis to help with the gardens' development, and display garden placements.
Eurobodalla is known for its temperate climate: cool winters and warm summers. The Garden site is five kilometres from the coast in a valley and is protected from immediate coastal influences.
Temperature
Compared to adjacent areas on the coast, the average temperature at the Garden is colder in winter and warmer in summer.
Eurobodalla often has slow-moving high-pressure systems during winter, resulting in fine, clear weather. Although heavy rain can occur in any month, on average the period from May to September has low rainfall. During summer, low-pressure influences can bring heavy rain.
Frosts
There are on average 20 days with frost each year at the Garden and most of these occur in late June and July.
Humidity
Batemans Bay usually has high humidity levels which reflect the coastal influence. These humidity levels are the closest indicator of levels likely to occur at the Garden, given its close proximity to the coast.
Tree species in the Garden, include:
- Eucalyptus elata
- Eucalyptus longifolia
- Eucalyptus piperita
- Eucalyptus globoidea
- Angophora floribunda
- Corymbia maculata
- Backhousia myrtifolia.
Casuarina spp. and Acacia spp. grow understorey in a large number of areas within the Garden.
Rainforest shrubs and small trees such as Backhousia spp., Prostanthera spp., Pittosporum spp. and Elaeocarpus spp. form the understorey along Deep Creek.
Many species of ferns (including some tree ferns) also occur in dense patches.