million years. Approximately 40 mya, the location of today's ranges and plains were flat, with a hard sedimentary capping. About 2 mya, block faulting raised the Mount Lofty Ranges, and much of the former land surface west of the ranges eroded away. The Gun Emplacement is a small remnant of this pre-erosion surface. It is a raised semi-circular flat area and has views over much of Adelaide from the southwestern corner of the park. The Emplacement is seen as an important regolith deposit, particularly for its role in understanding Adelaide's landscape's evolution. The Emplacement was declared a Geological Monument in 1978 for this geologic importance as well as its aesthetic and recreational value. Across the park, different ages of exposed rocks are seen. Stoneyfell quartzite, composed mostly of quartzite with sandstone and some siltstone, is the youngest. Woolshed flat shale is older and is composed of siltstone, dolomite and some sandstone. The oldest regular exposure is Montacute dolomite, which is a blue-grey dolomite with magnesite, siltstone and sandstone. Quarries in the south of the park have been mined for Stoneyfell Quartzite. This type of quartzite is a clean, white, feldspathic quartzite with interbedded thin siltstone layers up to thick occurring at gaps of . Ripple marks in this rock clearly indicate its shallow water origin. Next to Newman's Nursery is a quarry with grey to blue silicaceous dolomite used for road material. It contains traces of pyrite and is overlain by phyllite. Tea Tree Gully freestone, as found in the largest quarry in the park, is a feldspathic sandstone bedded with quartzite. Decay of the feldspar has enabled it to be cut and dressed as a quality building stone. The Tea Tree Gully iron (or silver) mine lies in an iron-rich fault zone. The ore body is ironstone, 150 m long, 50 m wide and 30 m thick (490 ft by 160 ft by 100 ft). It is primarily limonite, detrital quartz and silica. It is thought to have been chemically deposited during the Paleogene and Neogene periods, 2 mya to 66 mya. Flora and fauna In the 1983 concept plan, 413 plant species were identified, including 124 that were not native to the park. The park was noted as one of the few remaining significant areas of bushland in the foothills. By 2006, the flora list contained 411 species, with 107 of these non-native. Five of the native species