4600 million years
"...or we can depict Mother Earth as a lady of 46, if her "years" are megacenturies. The first seven of those years are wholly lost to the biographer, but the deeds of her later childhood are to be seen in old rocks in Greenland and South Africa. Like the human memory, the surface of our planet distorts the record, emphasising more recent events and letting th rest pass into vagueness - or at least into the unimpressive joints in worn down mountain chains.
Most of what we recognise on Earth, including all substantial animal life, is the product of the past six years of the lady's life. She flowered, literally in her middle age. Her continents were quite bare of life until she was getting on for 42 and flowering plants did not appear until she was 45 - just one year ago. At that time, the great reptiles, including the dinosaurs, were her pets and the break-up of the last supercontinent was in progress.
The dinosaurs passed away eight months ago and the upstart mammals replaced them. In the middle of last week, in Africa, some man-like apes turned into ape-like men and, at the weekend, Mother Earth began shivering with the latest series of ice ages. Just over four hours have elapsed since a new species calling itself Homo Sapiens started chasing the other animals and in the last hour it has invented agriculture and settled down. A quarter of an hour ago, Moses led his people to safety across a crack in the Earth's shell, and about five minutes later Jesus was preaching on a hill further along the fault line. Just one minute has passed, out of Mother Earth's 46 "years", since man began his industrial revolution, three human lifetimes ago. During that time he has multiplied his numbers and skills prodigiously and ransacked the planet for metal and fuel."
Nigel Calder, The Restless Earth (1972)
Now, however much this short passage offends my feminist sensibilities (Mother Earth, woman and nature, man began his industrial revolution etc.), i have to say, this was what inspired me and my love for geography,
all those many years ago back in junior college.
Meanders, glaciers, Dartmoor, continental drift, fluvial geomorphology, valleys and plateaus, overland flow,waterfalls groundwater, stalagmites and stalactites.
And miss j's little globe that is always on the verge of falling apart.
I'm a self-avowed human geographer today, and i do wish i can remember more of what i learnt in physical geography classes in jc.
Yet, what hasn't changed is how i still believe geography provides a unique lense through which one can come to understand both the human and physical landscape, and the world around us.
I ♥ geography! :)