arms across the mouth of the gorge, he could have diverted the river
down the side valley here."
"It looks possible," she laughed. Tamre giggled in sympathy, not
understanding a word of what they were saying, but enjoying himself
immensely.
"I would need a dumpy level to take some shots of the actual fall of the
land. It can be very deceptive, but with the naked eye it does look
possible, as you say." He shaded his eyes and looked up the bluffs on
each side of the waterfall. They formed two craggy portals of limestone,
between which the river roared as it plunged over the lip.
"I would like to climb up there to get a clearer picture of the layout
of the terrain. Are you game?"
"Try and stop me,', she challenged him, and led the climb. It was a
heavy scramble, and in some places the limestone was rotten and
crumbling dangerously. However, when they came out on the summit of the
eastern portal they were rewarded with a splendid overall view of the
ground below.
Directly to the north, the escarpment rose like a sheer wall with its
battlements crenellated and serrated. Above and beyond it there was a
dream of further mountains, the high peaks of the Choke, blue as a
heron's plumage against the clearer distant blue of the African sky.
All around them were the badlands of the gorge, a vast confusion of
ridges and spines and reefs of rock of fifty different hues, some
ash-grey and white, others black as the hide of a bull buffalo, or red
as his heart blood. The river in bush was green, the poisonous vivid
green of the mamba in the treetop, while further from the water the
scrub was grey and sear, and along the spines of the broken kopjes stood
the stark outlines of ancient drought-struck trees, their tortured limbs
twisted and black against the sky.
"The picture of devastation," Royan whispered as she looked around her,
'untamed and untaniable. No wonder Taita chose this place. It repels all
intruders."
They were both silent for a while, awed by the wild grandeur of the
scene, but as soon as they had recovered from the exertion of the climb
their enthusiasm resurfaced.
"Now you can get a good picture of it." Nicholas pointed down into the
valley below them. "There is a clear divide at the fork of the valley.
You can see the natural fall of the ground. There, from that side of the
gorge to that point below us, is the narrowest part. It is a neck where
the river squeezes through - the natural site for a dam." He swivelled
and pointed down to the left of where they sat.
'it would not take much to spill the river into the valley.
Once he had finished whatever he was up to in the chasm, it would taken
even less to break down the wall of the dam and let the river resume its
natural course again."
Tamre watched their faces eagerly, turning his head to each speaker in
turn, uncomprehending, but aping Royan's expression like a mirror. If
she nodded he nodded, when she frowned he did the same, and when she
smiled he giggled happily.
"It's a big river." Royan shook her head, while Tamre wagged his from
side to side in sympathy and looked wise.
"What method would he have used? An earthen dam?
Surely not?" i "The Egyptians used earthen canals and dams for a great
many of their irrigation works,'Nicholas mused. "On the other hand, when
they had rock available to work with ..", they used it extensively. They
were expert masons. You have stood in the quarries at Aswan."
"Not much topsoil here in the gorge," she pointed out.
"But on the other hand, there is plenty of rock. It's like a geological
museum. Every type of rock that you could wish for."
"I agree," he said. "Rather than an earthen wall, Taita would most
probably have used a masonry and rock fill.
That is the type of dam the ancients built in Egypt, long before his
time. If that is the case, there is a chance that traces of it have
survived."
"Okay. Let's work on that hypothesis. Taita built a dam of rock stabs,
and then he breached it again. Where would we find the remains of it?"
"We would have to start searching on the actual site," he answered.
"There at the neck of the gorge. Then we would have to search downstream
from there."
They scrambled down the slope again, with Tamre picking out the easiest
route for Royan, stopping to beckon her whenever she faltered or paused
for breath. They came out in the neck of the valley and stood on the
rocky bank of the river, looking about them.
"How high would the wall have been?" Royan asked.
"Not too high. Again, I can't give you a precise answer until I have
shot the levels." He climbed a little way up the side of the wall. There
he squatted and turned his head back and forth, looking first down the
length of the valley and then towards the lip of the waterfall that
dropped into the mouth of the chasm.
Three times he changed his position, on each occasion moving a few paces
higher up the slope. The cliff became steeper the higher he climbed. In
the end he was clinging precariously to the side of it, but he seemed
satisfied. Then he called down to her.
"I would say this is about it, where I am now. This would be the height
of the dam wall. It looks about fifteen feet high to me."
Royan was still standing on the bank, and now she turned and stared
across at the far bank of the river, estimating the distance to the
limestone cliff rising above it.
"Roughly a hundred feet across," she shouted up to him.
"About that," he agreed. "A lot of work, but not impossible."
"Taita. was never one to be daunted by size or difficulty." She cupped
her hands around her mouth to shout up to him. "While you are up there,
can you see any sign of works? Taita would have had to pin the dam wall
into the cliff."
He scrambled along the cliff, keeping to the same level, until he was
almost directly above the falls and could go no further. Then he slid
down to where Royan and Tamre waited.
"Nothing?" she anticipated, and he shook his head.
"No, but you can't really expect that there would be anything left after
nearly four thousand years. These cliffs have been exposed to wind and
weather for all that time. I think our best bet will be to look for any
surviving blocks from the dam wall that might have been carried away
when Taita. breached it to flood the chasm again."
They started down the valley, where Royan came upon a chunk of stone
that seemed to be of a different type from the surrounding country rock.
It was the size of an oldfashioned cabin trunk. Although it was
halfcovered by undergrowth, the uppermost end - the one that was exposed
- had a definite right-angled corner to it. She called Nicholas across
to her.
"Look at that." Royan patted it proudly. "What do you think of that?"
He climbed down beside herand ran his hands over the exposed surface of
the stab. "Possible," he repeated. "But to be certain we would have to
find the chisel marks where the "old masons started the fracture. As you
know, they chiselled a hole into the stone, and then wedged it open
until it split."
Both of them went over the exposed surface carefully, and although Royan