Dinosaurs in St. Marylebone
Christchurch, in Bell Street, St Marylebone
Christchurch is built of Bath Stone, an oolitic Middle Jurassic limestone 172-162 million years old. The stone is an orange-brown colour and is a true freestone, which means that it can be cut well in any direction. This is because it consists of grains of lime which have each become coated with a skin of lime to form even sized pellets, like cod's roe, hence the name (oo - egg, lithe - stone). The `eggs' were deposited chemically in layers at the bottom of a shallow, clear sea. The white sand on the beaches of Jamaica are oolites and Oolitic Limestone is being laid down there all the time.
London is full of York Stone which splits easily into paving slabs. Bath Stone cannot be split in this way. It is a solid mass of tiny grains, not a series of sheets. York is a paving stone: Bath Stone is a carving stone.
Bath Stone can be carved freely in any direction because it does not split along bedding planes but it cannot be highly polished. The individual grains merely break off. Polishing it would be like trying to polish chip- board.
A greatly magnified section showing the small spheres,
about 1-2mm in diameter, like fish eggs.
Imaginary scene during the Lower Oolitic Period when the stone for the building below was being formed.
This could have been the environment of Bath and Cheltenham during the Lower Jurassic Period, 172-195 million years ago. Perhaps on the back of one of the cut stone blocks if Christchurch, turned away from our sight by a careful mason, may be the foot print of a dinosaur.
A Victorian woodcut showing an artist’s impression of the Jurassic Coast.
This was the environment of Bath and Cheltenham during the Lower Jurassic Period, 172—195 million years ago. Each time the cliffs were eroded away the fossils of strange creatures were revealed to general bewilderment.
January 2, 2013