Garza turned and stared at Sandecker with a curious expression. 'This isn't a sea project, Admiral?'
'No, I'm sorry you weren't fully informed, Herb. But I'm afraid we'll have to keep the real purpose of our work a secret for a little longer.'
Garza shrugged indifferently. 'You're the boss.'
'All I need is a direction,' said Mifflin.
'South,' Pitt told him. 'South to the Rio Grande.'
They dropped down the coast along the Intercoastal Waterway, passing over the hotels and condominiums of South Padre Island. Then Mifflin ducked the green helicopter with the NUMA letters on the side under a layer of popcorn puffed clouds and swung west below Port Isabel where the waters of the Rio Grande spilled into the Gulf of Mexico.
The land below was a strange blend of marsh and desert, flat as a parking lot, with cactus growing amid tall grass. Soon the city of Brownsville appeared through the windshield. The river narrowed as it flowed under the bridge connecting Texas to Matamoros, Mexico.
'Can you tell me what we're supposed to survey?' asked Garza.
'You grew up in the Rio Grande Valley, didn't you,' Sandecker queried without answering.
'Born and raised up river at Laredo. Took my undergraduate courses at Texas Southernmost College in Brownsville. We just passed over it.'
'Then you're familiar with the geology around Roma?'
'I've conducted a number of field trips in the area, yes.'
It was Pitts Turn. 'Compared to now, how did the river flow a few centuries after Christ?'
'The stream wasn't much different then,' answered Garza.
'Oh, sure, the course has shifted during earlier flooding, but seldom more than a couple of miles. Quite often over the centuries it returned to its previous course. The major change is that the Rio Grande would have been considerably higher then. Until the war with Mexico the width ran from two hundred to four hundred meters. The main channel actually was much deeper.'
'When was it first seen by a European?'
'Alonzo de Pineda sailed into the river's mouth in 1519.'
'How did it stack up to the Mississippi back then?'
Garza thought a moment. 'The Rio Grande was more akin to the Nile.'
'Nile?'
'The headwaters begin in the Rocky Mountains of Colorado. During the spring flooding season, as the winter snows melted, the water swept down the lower reaches in huge surges. The ancient Indians, like the Egyptians, dug ditches so the high water ran to their crops. That's why the river you see now is a mere trickle of its former self. As the Spanish and Mexican settlers moved in, followed by the Texas Americans, new irrigation works were built. After the Civil War, railroads brought in more families and ranchers, who siphoned off more water. By 1894, shallow and dangerous shoals put an end to steamboating. If there had been no irrigation, the Rio Grande might have been the Mississippi River of Texas.'
'Steamboats ran on the Rio Grande?' asked Lily.
for a short time traffic was quite heavy as trade developed upland down and on both sides of the river. Fleets of paddle steamers made regular runs from Brownsville to Laredo for over thirty years. Now, since they built the Falcon Dam, about the only craft you see on the lower river are outboard boats and inner tubes.'
Could sailing vessels have navigated as far as Roma?'
asked Pitt.
'With room to spare. The river was easily wide enough for tacking. All a ship with sails had to do was wait for easterly offshore breezes. One keelboat made it as far northwest as Santa Fe in 1850. '
They fell quiet for a few minutes as Mifflin followed the meandering turns of the river. A few low, rolling hills appeared. On the Mexican side, little towns first settled nearly three hundred years ago sat in dusty seclusion. Some houses were built of stone and adobe and topped by red tile, while the outskirts were dotted with small primitive huts having thatched roofs. The agricultural part of the valley, with its citrus groves and fields of vegetables and aloe vera, gave way to and plains of mesquite trees and white thistle. Pitt expected a muddy brown river, but the Rio Grande pleasantly surprised him by running a deep green.
'We're coming up on Roma now,' announced Garza. 'The sister city across the river is called Miguel AlemAn. Not much of a town. Except for sonic tourist curio stores it's mostly a border crossing on the road to Monterrey.'
Mifflin pulled up and soared over the international bridge, and then dropped low on the river again. On the Mexican side men and women were washing cars, mending fishing nets and swimming. Along the bank a few pigs wallowed in the silt. On the American side a yellowish sandstone bluff rose from the riverbank up to the main section of downtown Roma.
The buildings appeared to be quite old and some were rundown, but all seemed in sound condition. One or two were in stages of reconstruction.
'The buildings look very quaint,' said Lily. 'There must be a lot of history behind their walls.'
'Roma was a busy port during the commercial and military boating era,'
Garza lectured. 'Prosperous merchants hired architects to design some very interesting homes and business structures. And they've lasted quite well.'
'any one more famous than the others?' asked Lily.
'Famous?' Garza laughed. 'My pick would be a residence built in the middle 1800s that was used as 'Rosita's
