Seashells on Normanby Island – Part 2

I enjoyed my first visit to Normanby Island so much that I went back a second time before I finished my Queensland holiday – and photographed some more seashells!

P.S. This is the 1000th Post I have published on Jessica’s Nature Blog.

COPYRIGHT JESSICA WINDER 2014

All Rights Reserved

Seashells on Normanby Island – Part 1

A wonderful assortment of beautiful tropical seashells lies on the coral beaches around Normanby Island. Normanby Island is one of the Frankland Island group which lies on the Great Barrier Reef off the Queensland Coast of Australia. As it is a National Park, you cannot collect and take away anything from the island. All these photographs were taken on the beach during the visit. Access to Normanby Island is somewhat limited and only one company was running trips to the island when I was there. Most of the visitors sailing to the island from the Mulgrave River were intent on diving and snorkelling on the living coral reefs around the island, a pleasure that was denied me as a non-swimmer. I contented myself with exploring the shores and enjoying the fabulous picnic provided.

COPYRIGHT JESSICA WINDER 2014

All Rights Reserved

The Big Button Shell

Button or Pearly Top Shell (1) - Trochus (Tectus) niloticus Linnaeus found on the shore of Normanby Island off the coast of Northern Queensland, Australia. The mother-of-pearl from this type of shell was and still is used commercially for making buttons and similar decorative objects. Trochus niloticus Linnaeus is a large heavy Top Shell with a lot of internal mother-of-pearl which has, in the past, been commercially exploited for use in button-making. Hence its common name of Button or Pearly Top Shell. The numbers are reduced now but shells are still found washed ashore. The examples shown here were photographed on Normanby Island near the Great Barrier Reef off the coast of Northern Queensland in Australia.

The island is a nature reserve and nothing can be removed. Whatever lives there, or is found there, stays there – so that it can be enjoyed by all subsequent visitors. Hidden among the trees on the island is a table top covered with some of the unusual or colourful treasures that have been picked up on the beach – comprising clams, cowries, cones, corals, cuttle bones, conchs, helmet and turban shells. The collection also includes several worn and faded specimens of this large Pearly or Button Top Shell – but none as splendid and intact as the ones I found (and left) on the strandline.

Button or Pearly Top Shell (2) - Trochus (Tectus) niloticus Linnaeus found on the shore of Normanby Island off the coast of Northern Queensland, Australia. The mother-of-pearl from this type of shell was and still is used commercially for making buttons and similar decorative objects.

COPYRIGHT JESSICA WINDER 2013

All Rights Reserved

Cay Sandstone or “Beach Rock”

Cay Sandstone or "Beach Rock" (1) - Layers of "Beach Rock" or Cay Sandstone recently formed by a natural cementation of coral and shell fragments in still shallow water at the edge of Normanby Island, one of the Frankland Islands, Queensland, Australia.

We are used to thinking of rocks as ancient structures that have been in place for millions of years but, of course, rocks are in the continual process of being formed. An example might be the way rivers carry erosion sediments downstream to form layers on the beds of seas, lakes, and lagoons. Or erupting volcanic lava solidifying on contact with air or water. On the coastline of Queensland in Australia the most easily visible type of present-day rock formation is that of cay sandstone, commonly called “beach rock”.

Beach rock forms very rapidly. It happens in warm shallow water close to coral reefs, where the combination of heat and evaporation, an abundance of dissolved calcium from pieces of coral and seashells, and the addition of phosphates from bird guano, lead to a cementing of all the loose fragments together to form hard concretions of rock. This is such a rapid way of rock building that it is sometimes possible to see man-made objects included in the concretion – apparently soft drinks cans have been recorded. More commonly seen are pieces of coral (sometimes still coloured), sea shells, and the impressions of plant remains such as Pandanus fruits.

The photographs in this post were taken mostly on the sheltered shore of Normanby Island where the beach rock layers form an almost continuous link and low-tide walkway to the neighbouring island. Large slabs of beach rock are prone to break off from the layers and rest on the shore. In other places deep deposits of algal-covered rock have started to wear into depressions and hollows that form new habitats for marine gastropods and crustaceans.

I travelled to Normanby Island on a tour with Frankland Islands Great Barrier Reef Cruise.

Cay Sandstone or "Beach Rock" (2) - Normanby Island is linked to an adjacent small island in the Frankland group by layers of "Beach Rock" or Cay Sandstone recently formed by a natural cementation of coral and shell fragments in still shallow water in Queensland, Australia.

COPYRIGHT JESSICA WINDER 2013

All Rights Reserved

Normanby Island Coral Shore 1

Normanby Island is one of the Frankland Island group off the coast of Queensland, Australia – opposite the Mulgrave River estuary. Unlike many of the cays and isles of the Great Barrier Reef, Normanby Island has a solid core of weathered metamorphic rock which represents the top of a coastal mountain range that has become submerged and separated from the mainland by a rise in sea level 6,000 years ago.

However, the island is surrounded by thriving populations of living corals visible through the clear azure blue waters. The beaches are mostly composed of coral fragments derived from the reefs with only a small portion of the beaches being soft coral sands. These pieces of coral are the bleached skeletons of the many colourful species that live off-shore.

The photographs in this post show a selection of the many fascinating natural shapes and patterns in the larger pieces of coral that I found on the beach during an all too brief trip out to the island. It was a wonderful experience. The short video clip below shows the waves crashing onto the coral shore – to share with  readers a taste of this tropical island paradise.

COPYRIGHT JESSICA WINDER 2012

All Rights Reserved