Geology

The coastline of the shire is dominated by Tumblagooda Sandstone, formed during the Ordovician period from sedimentary and volcanic rocks and consisting of fine to coarse grained red-bed sandstone with minor siltstone. The geology underlying Northampton town site is part of the Northampton Complex, comprised of granite rock, paragneiss, quartz and feldspar. The underlying geology east of Kalbarri is the Winning Group, formed during the Cretaceous period from sedimentary and volcanic rocks and consisting of undivided shale, siltstone, marl and basal sandstone. The north western portion of the shire is dominated by the Cape Range Group which is comprised of toolonga cacilutite, cardabia calrenite and the Tamala limestone.

The eastern portion of the shire is located on the Nangetty formation, formed during the Carboniferous-permian period from sedimentary and volcanic rock and consisting of diamictite, shale and sandstone. The south west portion of the shire is located on the Cattamarra Coal Measures, formed during the Jurassic period from volcanic and sedimentary rocks and consisting of siltstone, shale, claystone, coal and sandstone. Underlying the Cattamarra Coal Measures is the Kockatea Shale formation, formed during the Triassic period from sedimentary and volcanic rocks and consisting of shale, siltstone and sandstone. The coastline consists of deep calcareous sandy soils overlying coastal dunes, low hills and limestone outcrops. Much of the area east of the coast consists of deep siliceous sandy coloured soils overlying undulating sand plains and low stony ridges. The soils over the Northampton Complex are red loamy duplexes and sandy or loamy gravelly soils. Small areas of red shallow loams and red-brown hardpan soils associated with relic drainage lines occurs in the east of the shire.

Environment

The shire is located within the Geraldton Hills (GES01) and Edel (YAL01) IBRA sub-regions and is characterised by sandy proteaceous heath, casuarina scrub, and low close acacia shrublands. The Edel subregion is unique because it is a transition zone for flora and fauna between the South West and Carnarvon Bioregions. Patches of Subtropical and Temperate Coastal Saltmarsh can be found in the shire. This is a nationally protected Threatened Ecological Community listed as vulnerable under Australia’s national environment law. The plant, animal and micro-organism community is found in the intertidal zone, often associated with estuaries. The plant community consists mainly of salt-tolerant vegetation (halophytes) including grasses, herbs, reeds, sedges and shrubs. Several Priority Ecological Communities occur in the shire, including Melaleuca Shrublands over exposed Kockatea Shale in the Port Gregory area, the plant assemblages of the Moresby Range System and the mallee-dominated Kalbarri Ironstone Community.  The shire is home to a number of endangered and endemic orchids and poorly known endemic reptiles such as the Blunt-nosed Blindsnake Anilios obtusifrons and the Stripe-sided Robust Slider Lerista axillaris. Important populations of Black-flanked Rock Wallaby Petrogale lateralis and Chuditch Dasyurus geoffroii live in Kalbarri National Park and the shire is also home to the furthest north known breeding population of endangered Carnaby’s Black Cockatoo Calyptorhynchus latirostris.