Living memory means recent. “Happened within living memory” means that people alive today remember it happening. In 1934, when my mother was born, the world was deep in the Great Depression. Unemployment was about 25%. The February that year – this time 88 years ago – was the coldest month on record for much of the US. A gallon of gas cost 10c, a pound of hamburger cost 12c. Of course, average income per year was $1600, so there’s that. My mother doesn’t remember all this because, I mean, she was a baby, but people alive today do remember all this. This is within living memory.
Historical time still means recent. Historical time means “time since reasonably reliable records started being kept by historical civilizations.” This means historical time encompasses about the past 5000 years or so. (I’m rounding it off, okay, don’t tell me the earliest Egyptian hieroglyphs were before that.)
Archeological time still means pretty recent. The Stone Age began about 3.3 million years ago and lasted until the beginning of historical time, basically. If we look at the founding of Rome to the modern day, that is 2725 years, more or less. We would have to step back that far 1100 times to get to the first stone tools. Think of that! How long from the founding of Rome to now and it was more than a thousand times longer to get from stone tools to Rome! That’s astounding.
This is still just a tiny step back into the past. All of archeological time is still pretty recent.
DEEP time means way, way back. I guess we could call the less deep part paleontological time, and the really deep part geologic time. Paleontological time is the kind that is really cool from a biological perspective.
If we stood up right now, right there in our living rooms, and pop, suddenly we stepped back a million years and looked around, the world would look pretty normal. I mean, except for civilization vanishing. The animals and plants and climate would be really similar to what we see right now. Canids in the subfamily Caninae had already outcompeted earlier canids in the subfamilies of Borophaginae and Hesperocyaninae; if you saw a canid, you would just say, “Oh look, a wolf,” or whatever. Modern horses had appeared. Mice looked like mice. Birds looked like birds. Sure, there were differences. Watch out for the saber-toothed tigers! But saber-toothed tigers looked a lot like modern tigers. You wouldn’t think, “Huh, what is that? Would you call that some kind of cat?” because obviously saber-tooted tigers were basically heavy-bodied modern big cats. With big canine teeth. But modern cats. The cat branch of Carnivora separated from the dog branch long before this, the bears and dogs separated long ago, the cats and hyenas separated long ago. The world looked normal. It looked modern. (Mostly modern.)
Anyway, if you looked around and snapped a picture and stepped back another million years, and repeated that 540 times, you would be in the Cambrian, at the dawn of life, and you would have seen a LOT of changes. And that is what Otherlands by Thomas Halliday does, except he takes bigger steps, probably because he didn’t want to include 540 chapters in his book. Halliday’s steps are uneven in the distance covered in time and space, but what he’s doing in this book is walking back through time, taking big steps, and bringing the reader along for the journey.
Looking out from Gargano, Italy, in the latest Miocene, more than 5 million years before the present day, it is hard to countenance the idea that, in a little over a year, swirling brine will be washing these stones. Even harder is to visualize this towering mountain, alone and proud, sending boats out into the intangible air, this sky becoming the centre of trade and warfare, filled with people, goods, armies and ideas for thousands of years. This clifftop will hold communities of fisherfolk, as a limestone promontory surrounded by the Mediterranean Sea. For now, the basin is drained, a salty, dry, inhospitable land reaching down kilometers into the depths of the Earth. From the Levant to Gibraltar, from the North African coast to the Alps, the Mediterranean has run dry.
Neither is this for the first time. As the tectonic plate beneath African and Arabia has pushed northwards, the once mighty Tethys Ocean has grown narrower and narrower, reduced to a small, enclosed sea between Afro-Arabia, Asia, and Europe – the Mediterranean. The only connection between this sea and the rest of the world’s oceans is a narrow gap between what will be Spain and Morocco – the Straits of Gibraltar. Through the last million years, the push of Earth’s plates has periodically closed the gap, with drastic impacts on its environment.
Halliday notes that various rivers pour 600 km3 into the Mediterranean basin per year, but that evaporation pulls 4700 km3 of water back out again. Because the Mediterranean repeatedly flooded with saltwater which then evaporated, because the land beneath the Mediterranean is so far below sea level, there are places where the salt deposits at the bottom of the Mediterranean are three km deep. When you stand at the bottom of that basin, five million years ago, you are standing in a bleak, salty desert where temperatures can reach 175 F (80 C), but it’s going to flood in a hurry when erosion opens up a channel through the Straits of Gibraltar. It’ll start with a trickle, but it isn’t going to stay that way. Water’s going to pour in with unimaginable force, rushing at forty miles an hour through a channel nine miles across, wide open to the full pressure of the Atlantic Ocean. This is the moment Halliday has chosen to show us.
… the Mediterranean to the west is almost full, but the east is as dry as it ever was. Four months after the Straits of Gibraltar first opened, this begins to change, as to the south a standing plume of mist, hundreds of meters tall, rises from the eastern edge of Sicily, visible from many kilometers away. The roar comes further south still, near the modern-day site of Syracusa. … as seawater begins to spill over the dam, the eastern basin will be filled by the greatest waterfall ever to have graced the Earth. It is nearly a mile high, one and a half times the height of the modern-day Angel Falls in Venezuela. The water pours over the escarpment at speeds of 100 miles per hour, and much of it turns to mist before it reaches the ground. Unlike the Straights of Gibraltar, where the descent into the western Mediterranean basin is gradual, weir-like, this is a true, sheer drop, where the force of an entire ocean is channeled into a single five-km-wide site.
This event, the filling of the Mediterranean Sea, marked the end of the Miocene and the beginning of the Pliocene. Obviously all this had massive consequences for the ecosystems of the region, which Halliday describes with special emphasis on the tendency of island faunas to become dwarfed (if the mainland species is big) or giants (if the mainland species is tiny). In broad terms, the fauna and flora of the region was modern. Giant “Terrible Moon Rats” (great name!) were basically top mammalian predators on the island of Gargano, which means they were about cat-sized. They were gymnures, insectivores, related to hedgehogs, though the Terrible Moon Rats weren’t spiny. Among other animals, these gymnures shared the island with giant rabbits (I mean, giant for rabbits, not really that big, about 25 lbs) called Nuralagus, which Halliday describes, accurately, as “wombat-like.” They did not look all that much like modern bunnies, though you can see they’re lagomorphs if you sort of squint.
And all this is close to the beginning, as Halliday then steps back a huge distance into deep time, another 30 million years, and from one continent to another – to Chile in the Oligocene. Then another eleven million years, this time to Antarctica – which here, smack dab in the Eocene Hothouse, is not frozen. The whole story of the Oligocene is a tale of catastrophic cooling and drying from the Eocene Hothouse, ice caps forming at the poles, forests dying out in massive regions, replaced by the brand-new plants called “grasses,” that spread out to form huge grasslands. The appearance and spread of grasses and grasslands led to my favorite ecosystems (savannahs) and the appearance of canids and big horses and the rest of the fauna that’s suited to grasslands. Here, in Antarctica, 41 million years ago, that shift from forest to grasslands hasn’t yet begun and à
The beach is filled with the shouts of seabirds, the older ones insistently calling for their mates, the young pretenders eyeing up possible nesting sites. Littered with the unicorn horns of turritellid sea snails, spiraled Polynices gastropods, and the smooth hooded platters of Cucullaea clams, the shingle has been turned into an exceptionally crowded breeding ground. … Around the beach, the slopes are steep and densely forested; a hanging wood of scale-barked southern beeches, Nothofagus, pours down the hillside. Interspersed among them are tight-packed conifers – monkey-puzzles, cypresses, celery palms – and all are garbed in epiphytes, those plants that grow entirely on the surfaces of others. Vines and lianas, ferns and hair-like mosses, set off by the complex, show-off inflorescences of the proteas, form a cloudy green palette.
Here we are, standing in a temperate coastal rainforest, a lot like the Pacific Northwest of the US and Canada, except in Antarctica. That means the days last all summer long, and when the sun finally sets, it doesn’t come up for three months, just as we see today, except the whole continent was covered in lush forest filled with organisms that had to deal with this remarkable solar cycle. Which they did. There were penguins here, in this beautiful forested Antarctica, but they were much, much bigger than modern penguins, with various species standing taller than I do (I’m short, but still) and the biggest species standing as tall as a tall human, about six feet, and weighing in at about 250 lbs. Their anatomy isn’t as specialized as modern penguins, but they’re well on their way and anybody would look at them and say, “Oh, look, giant penguins.”
Another twenty million years back in time, to Montana. The world has ended. Two years ago, a piece of rock at least ten km long appeared high in the sky to the north, traveling southwards and westwards at thousands of meters per second. Halliday likes disaster stories, I gather. But he walks forward through this chapter, describing the resurgence of life and the rise of mammals. A new age begins, with new gods, and new worlds. After death, life; after extinction, speciation. But we’re not moving forward, remember. In the next chapter, Halliday steps back again, as far again as we’ve come already, to China 125 million years ago, an age of splendor, as we have to step hastily out of the way of giant sauropods. Early birds such as Confuciusornis share the skies with pterosaurs.
Halliday takes nine more steps back after that, each taking the reader farther back through deep time, all the way to the Ediacaran fauna of Australia, 550 million years ago, pausing each time to sketch the scene. Anybody interested in description might enjoy this time-traveling story of planetary history; and Halliday’s a fine stylist too, often building layered paragraphs of evocative sentences. I wouldn’t say this book is as amazing as An Immense World by Ed Yong, but on the other hand, it would certainly work well as a companion volume, one to showcase animal diversity right now, a snapshot of present time; and the other to showcase animal and plant diversity through time.