Seacliff - fossil shark teeth

This site is located on private property and permission is required from the land owner and the Dunedin City Council

Seacliff – this township is probably sitting on one of the most unstable areas of land in the country. The countryside here is very prone to slipping due to Abbotsford mudstone / Caversham sandstone mix. Down on the rocky beach are exposures of both – more so the sandstone. On occasion the greensand formation is exposed and it was here the sharks tooth was found (see enlarged photograph). The greensand can be at times very wet. Other fossils can be observed in both the greensands and Caversham sandstones primarily.

The beach is made up of round cobbles of basalt interdispersed with large blocks of columnar basalt. Close inspection of some of these cobbles reveals cavities containing either calcite or naturlite or both.

Below is a summary of the Landslides in the Kilmog Hill – Seacliff Area by Martin L Stout Visiting Engineering Geologist August 1971 – NZ Geological Survey Lower Hutt DSIR.

The area is dominated by a series of fairly small landslides, which may in turn all be contained within one extremely large massive landslide

Geology within the area has been modified so extensively by the moderately large landslides that it is extremely difficult to produce a bedrock geological map.

Many of the volcanic rocks in the area have been rafted down slopes on top of the moving slides, and despite the presence of numerous volcanic boulders on the surface, are probably not in their original position. This can be well documented in the area and less so in others. Some of the higher hills in the area could be volcanic vents, but with present exposures it is impossible to confirm this, and in fact to determine if the volcanic debris in the higher hills has been involved in older land sliding.

Blocks of columnar joined basalt from a dike, up to 10 meters across are along the beach below the community of Seacliff have been carried at least 350m down the slope by slides and then in turn probably moved in storm waves

The age of the slips (original) is unknown; however the writer feels that whenever large landslides occurred extending below present sea level, they could be associated with a period of extremely heavy precipitation and runoff between 13,000 and 17,000 B.P.