Monday, December 25, 2006

Swanage



The hard banks of limestone form headlands while softer clays have been eroded into bays. Boat trips offer a fabulous view of the 80 million year old chalk stacks of Old Harry Rocks, the most easterly end of the Jurassic Coast. At Ballard Down the chalk ridge appears and the almost vertical layers of the chalk can only be seen from the sea. At one time, the ridge ran right across to the needles on the Isle of Wight

There is a Heritage Centre at Swanage and boat trips are available to Poole Harbour

Wednesday, December 20, 2006

Monday, December 18, 2006

Friday, December 15, 2006

World Changes during the Triassic, Jurassic and Cretatious Era's


The super-continent of Pangea

During the Triassic era, 240 million years ago, one hemisphere was dominated by a vast ocean while the other hemisphere was dominated by a great super-continent. Pangea. This great landmass included all of what is now known as North America, Europe, North Asia. Africa, South America, India, Australia and Antartica

During Triassic times, Pangea moved gradually northwards. At the end of the permian period, very low sea levels and climate change coincided with a major extinction event. Since then sea levels have risen again allowing a slow recovery of marine life such as corals on land - tropical coal forming forests and swamps diminished as climates got warmer and drier

During the Jurassic era, 170 million years ago, the world was a warmer, less varied place than it is today. There were probably no ice caps at the poles for much of this time. The mild conditions made for much higher sea levels resulting in a smaller area of dry land but extensive shallow continental seas, which teemed with life.

The huge continent of Pangea was splitting up, and familiar modern landmasses such as North America and Eurasia were begginning to appear. Both the North and South Atlantic oceans began to open up. At the same time the ancient tethys ocean began to close

The Cretatious period spanned almost 80 million years from 142 million to 65 million years ago. During this time the world began to take on a familiar look as lands that had once made up the super-continent of Pangea pulled apart. The newly formed Atlantic Ocean extended north and southwards, seperating Africa and Eurasia from the Americas. The continents of Africa, India, Antartica and Australia began to move apart about 120 million years ago as new oceans formed between these constiuents of ancient Gondwana. Asia still had an unfamilliar form, with lands that are now part of its southern edge, such as Indochina and India, still seperate islands.

By about 90 million years ago, the distribution of the contients was looking more familiar. The Atlantic ocean seperated the new world of of the Americas from the old world of Europe, Asia, and Africa. Much of Asia was assembled, except for India. Australia still languished in the deep south, attached to Antartica and India was still attached to Madagascar

Source: The Atlas of the Prehistoric World and Wikipaedia

Monday, December 11, 2006

Budleigh Salterton

Budleigh Salterton has one of the oldest stories of the Jurassic Coast. A story that is also spread out along the length of this coast and beyond

To the west of the sea front lie the famous Budleigh Salterton Pebble Beds. The pebbles are composed of hard quartzite identical to 440 million year old rocks found in Northern France. The pebbles were formed and transported in one of the giant rivers that flowed into the Triassic desert about 240 million years ago

Over the last few thousand years the pebbles have been falling from the cliffs and today form the bulk of the beach at Budleigh Salterton. The larger cobbles and pebbles are very hard and unlike any other rock type found in Southern England. As a result they survive as they are transported along the coast by the waves. They can be seen from Slapton Sands in Devon to Hastings in Sussex

Source: The Official Guide to the Jurassic Coast

Saturday, December 09, 2006

Durdle Door