Editing Ku-ring-gai Chase National Park (section)

==Geology==
[[File:Tessellated Elvina.jpg|[[Tessellated pavement]] near the Elvina Track on the Park's Lambert Peninsular|thumb|left]]
Ku-ring-gai Chase is part of the [[Hornsby Plateau]], a massive block of sandstone tilting upwards to the north. The park comprises a plateau with an elevation of generally 150–200 m above sea level. Between 250 and 200 million years ago, sand silt and mud was deposited by rivers across flood plains.<ref name="NPA South 313"/> These formed the [[shales]], flagstones and sandstones of the [[Narrabeen Group]] that outcrop along the foreshores and ridges. Higher areas of the park are underlain with pink, white and orange layers of [[Hawkesbury Sandstone]] that contain small beds of shale. [[Wianamatta Group]] shale is present in the higher points of the park. The park's terraced landscape is due to the horizontal arrangement of these sediment layers.<ref name="NPA South 313">{{cite book |last1=Wright |first1=Peter |title=The NPA Guide to National Parks of Northern New South Wales |date=1991 |publisher=Southwood Press, Pty Ltd |location=Marrickville, New South Wales |isbn=0-959-91608-3 |pages=313–323 }}</ref>

Other rock types in the park are less common. Soils derived from the [[Narrabeen group]] of shales are around the eastern shore of the Lambert Peninsula, particularly around [[Elvina Bay]] and [[Lovett Bay]]. These richer soils provide for a vegetation type different from that of the sandy ridge top soils, providing for forests of spotted gums ([[Corymbia maculata]]) with forest oaks as a secondary layer. Eroded remnants of volcanic dykes occur including at Resolution Picnic Area at [[West Head]] and Campbells Crater near [[Cowan, New South Wales|Cowan]], which provide for forests of Sydney blue gum ([[Eucalyptus saligna]]).

More recent volcanic activity has forced small intrusions of igneous rock into the sandstone. A band of [[dolerite]] runs across the [[West Head]] peninsula near White Horse Beach, providing fertile soils for a distinct group of plants. The Smith's Creek area has intrusions of [[breccia]].<ref name="NPA South 313"/>

The plateau is divided into separate sections by the steep valleys of [[Cowan Creek]], [[Coal and Candle Creek]], and [[Smiths Creek (New South Wales)|Smiths Creek]]. These "flooded" or "drowned" valleys, knowns as [[ria]]s, were eroded into the sandstone much deeper than the current sea level during the glacial phases of the [[Pleistocene]] ice age. When the ice caps melted about 10,000 years ago, the sea levels rose and flooded the valleys of the park, and separated [[Lion Island (New South Wales)|Lion]] and [[Scotland Island|Scotland]] islands from the mainland. The tributaries of Pittwater and Cowan Creek became bays and inlets along and extended shoreline.<ref name="NPA South 313"/>

The dominant rock type is [[Hawkesbury Sandstone]] which determines the topography and the vegetation in the sandy soils. Sandstone cliffs, rocky and outcrops, and worn caves are common throughout the park.

Indigenous people engraved the flat sandstone outcrops.

[[Tessellated pavement]]s are found in the park whereby regular chequered patterns in the stone form along fault lines and lines of weakness.

The park's highest point is 246 m at Willunga Trig near West Head Road which runs along the ridge of the Lambert Peninsula.