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November 17, 2007
I've been invited to join my colleague from Ain Shams University, Dr. Strougo, on a field expedition to a site in the Western Desert. It's called Wadi Al-Hitan, or Valley of the Whales, and it's one of the most remarkable paleontological sites in the world. Most notably it's a treasure trove of fossil archaeocetes, the earliest whales so early in fact that they retain the feet of their terrestrial ancestors. In addition to the large number of these remarkable fossils, there are also remains of Sirenia (a group of marine mammals whose modern, living members include manatees and dugong), many types of fossil fish, turtles and countless invertebrates.
There are also countless nummulite tests, the giant, single-celled organisms whose symbiotic relationship with photosynthetic algae interests me so much. The rocks in Wadi Al-Hitan capture an interesting transition in the evolutionary story of Nummulites, and I'll have the chance to sample across a time when the largest members of the group disappear and give way to their much smaller relatives.
I had the opportunity to visit Wadi Al-Hitan last year as a tourist, but this time I'll be visiting as a researcher, which is much more exciting. Dr. Strougo will be meeting up with a team of scientists who are mapping the geology of the Valley and searching for new fossils. As a graduate student new to this study area, I'll be a beneficiary of their expertise as I collect my nummulite samples.
November 18, 2007
A drive through time
It's mid-afternoon by the time we escape the congestion of one of the world's largest "megalopolises" (nearly 30 million people, and counting) and follow the open road south through the Nile Valley. The landscape changes to green fields, and the dilapidated black-and-white taxis of the city give way to farmers driving donkey carts. For someone like me, used to the technological wonderland of urban America, the peaceful, rural life of the valley is like a glimpse into the past.
Egypt is sometimes called "a gift of the Nile," and the evidence for this sentiment is obvious as we turn away from the valley to head out into the surrounding landscape. About 96% of Egypt is desert, and life clings to the banks of the Nile. Although new desert-reclamation projects are underway now, historically only the nomadic Bedouin tribes could survive the vast, empty heat of the deserts. There are some plants and animals specially adapted to this severe habitat like a snail that buries itself for years at a time in the dry river beds (wadis) of the eastern desert, only to remobilize when a good rain falls (so cool!) but the casual visitor is unlikely to see many, if any of them. Looking out over the terrain, I can't decide if it looks more like the moon or Antarctica the white sands stretching all the way to the horizon like ancient snow.
We pass by the man-made lakes of Wadi El-Rayan both getting smaller and saltier every year and then nothing but desert lay before us. It's called the Western Desert in Egypt because it lies to the west of the Nile, but it's also the eastern reach of the great Sahara Desert, which spans all of North Africa from the Red Sea to the Atlantic. It covers an area of 3,500,000 square miles nearly the size of the United States. It's difficult to imagine so much emptiness, even when you're in it.
Dr. Strougo, who has a keen interest in echinoids, (the group that includes things like sand dollars, starfish, and sea urchins) has collected a sack full of fossil sand dollars. We stand at the top of the outcrop and compare our loot as the sun slips closer to the western horizon. We talk about the local stratigraphy or rather Dr. Strougo talks and I ask questions.
The rocks here were originally deposited in the warm, shallow coastal waters at the southern edge of the Tethys Sea from about 48 to 33 million years ago. Since then, movements of the Earth's crust have caused them to be tilted ever so slightly, so that as we travel roughly north, we will also be traveling from older to younger rock beds.
Today we've traveled from the modern hustle of Cairo all the way back to an ancient sea floor. For the next two days, we'll slowly be working our way forward again through the Eocene rocks that tell the story of a long lost time and place.
The few rooms available are all full, so Dr. Strougo and I go out to set up tents for ourselves. I'm a pretty enthusiastic camper at home, so I'm excited to be sleeping out under the desert sky. I even tromp off into the desert valley to get away from the lights and the sound of the generator. There isn't much of a moon, but I make my way toward a big rock sitting below a ridge. The desert floor is covered in bits of pointy rock, broken seashells, bone fragments and jagged Nummulites, so I'm pleased when I find a small depression full of fine soft sand to make my home.
For the next 15 minutes I curse and squint and spit sand as I try to re-secure my tent with my eyes closed, because I'm afraid they'll be scoured out of my head if I open them. I never appreciated how much being down in the river valley protects Cairo from the full fury of desert windstorms. It's like a hurricane full of sand. It's pure evil.
I find some big chunks of nummulitic rock to tie my tent lines too Nummulites to the rescue! I seal up the tent as well as I can, but I still have to wrap my head in a t-shirt to keep the sand from taking off the top layer of skin. Somehow, I eventually sleep.
November 19, 2007
The transitional beds
There are two working pick-up trucks at the camp, each with a designated driver and with good reason. Desert driving requires a great deal of skill and knowledge of the terrain. It's easy to get stuck in the sand, or worse, disoriented and lost. One of the other researchers tells me that even experienced drivers have gotten confused out in the desert and never come back.
Dr. Strougo and I will be going with another researcher in one truck to look at a bed where the last of the giant Nummulites appear. You can actually walk up the side of the outcrop and see how they dwindle away, becoming less and less abundant in the rocks, replaced by another kind of foraminifera called Discocyclina. Dr. Strougo will be collecting his own geologic samples for the mapping of the area.
We work from about 7:30 a.m. when we reach the outcrop, until mid-afternoon. Except for a short lunch break it's pretty much non-stop note taking, picture taking, and hammering out samples. Then we drive to an area called the Side Valley. Here, the rocks are from the Upper or Late Eocene, meaning younger than the ones we've been looking at. Here, I find the small nummulite species that fully replaced their truly giant predecessors. Looking down at the lentil-sized specimen, I realize that an era has ended for the Nummulites. Never again in their evolution did they achieve the diversity, the size … the grandeur, that they left behind in the Middle Eocene. What happened?
At the end of the day, we sit near the truck to relax for a minute. Dr. Strougo has found some more interesting echinoids, and he's wrapping them in toilet paper and stuffing them into matchboxes so they don't break (they're quite fragile). Our other colleague thinks he may have found another whale fossil, and he's excited to tell the others about it so that they can come and do some digging tomorrow. All in all, it's been a successful day.
All that's left to do is move my tent behind a rock so that I don't get blown off the face of the planet again tonight.
November 20, 2007
The "small" Nummulites
We hike around the valley, starting with a bed that until recently, everyone thought was the fossil remains of a mangrove forest. Some German scientists have taken another look, however, and they claim that they aren't mangrove roots, they're clam burrows. Whatever they are, Nummulites liked living around them.
We make our way up onto the cliff where there are the fossil remains of huge, incredible burrows filled in with yet more Nummulites. Once I collect my samples, we spend the rest of the afternoon walking higher up the outcrop, moving forward in time. The ranger helps me identify some of the fossils we find the giant oyster Pycodonta and casts of Turritella (a kind of gastropod, or snail). He also shows me a complete archaeocete skeleton that's still trapped inside the cliff.
The day slips by quickly, and I have to hurry up to the visitor's center to meet the car coming to pick me up. My driver thinks we're going straight back to Cairo, but I make him stop twice along the dirt road back to civilization so that I can take a few more notes and collect a few more loose specimens. I'd like to stay longer, but I'm leaving for a longer field trip in two days out to the Red Sea coast. I'll be leaving the mysteries of Nummulites for a while and focusing instead on the fossil coral reefs. It's going to be great!
All photos by Lorraine Casazza.
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