Tunnels by Roderick Gordon Page A

and tossed it over to Chester, who caught it and examined it with a bewildered expression.
    "I'm sorry, I don't understand. What's important about this?"
    "It's limestone . This infill has bits of limestone in it. Feel the surface of the rock. It's chalky — totally the wrong texture for sandstone. That's particulate ."
    "Particulate?" Chester asked.
    "Yes, much more grainy. Hang on, let me check to make sure I'm right," Will said as he produced his penknife and, folding out the largest blade, used it to pick at the clean face of another piece of the rock, talking the whole time. "You see, they're both sedimentary rocks, and they look pretty much the same. Sometimes it's quite hard to tell the difference. The tests you can use are to dropacid on it — it makes limestone fizz — or look at it with a magnifying glass to see the coarser quartz grains you only get in sandstone. But this is the best method by far. Here we go," Will announced as he took a minute flake of the stone he'd pried from the sample and, to Chester's amazement, slipped it off the blade and into his mouth. The he began to nibble it between his front teeth.
    "What are you doing , Will?"
    " Mmmm ," Will replied thoughtfully, still grinding it. "Yes, I'm pretty sure this is limestone… You see, it breaks down into a smooth paste… If it was sandstone, it'd be crunchier, and even squeak a little as I bit it."
    Chester winced as he heard the sounds coming from his friend's mouth. "Are you serious? Doesn't that crack your teeth?"
    "Hasn't yet." Will grinned. He reached into his mouth to reposition the flake and chewed on it for a little longer. "Definitely limestone," he finally decreed, spitting out what was left of the flake of rock. "Want a taste?"
    "No, I'm fine, really," Chester replied without a moment's hesitation. "Thanks anyway."
    Will waved his hand in the direction of the roof over the cave-in. "I don't believe there'd be a deposit — an isolated pocket of limestone — anywhere near here. I know the geology of this area pretty well."
    "So what are you getting at?" Chester asked with a frown. "Someone came down here and blocked up the tunnel with all this stuff?"
    "Yes… no… oh, I don't know," Will said, kicking the edge of the huge heap in frustration. "All I do know is that there's something very funny about all this."
    "It might've been one of the gangs. Could it be the Clan?" Chester suggested, adding, "Or maybe even the Click?"
    "No, that's not likely," Will said, turning to survey the tunnel behind him. "There'd be other signs that they'd been here. And why would they just block up this tunnel? You know what they're like — they would've wrecked the whole excavation. No, it doesn't make sense," he said, bemused.
    "No," Chester echoed.
    "But whoever it was, they really didn't want us to go back in there, did they?"
     
    * * * * *
     
    Rebecca was in the kitchen doing her homework when Will returned home. He was just slotting his shovel into the umbrella stand and hanging his yellow hard hat on the end of it when she called to him from around the corner.
    "You're back early."
    "Yeah, we had some trouble in one of the tunnels and I couldn't be bothered to do any digging," he said as he slumped down dejectedly in the chair on the opposite side of the table.
    "No digging?" Rebecca said with mock concern. "Things must be worse than I thought!"
    "We had a roof fall in."
    "Oh, right…," she said remotely.
    "I can't figure out what happened. It couldn't be seepage, and the really odd thing was that the infill…," he trailed off as Rebecca rose from the table and busied herself at the kitchen sink, clearly not listening to a word he was saying. This didn't bother Will unduly; he was used to being ignored. He wearily rested his head in his hands for a moment, but then raised it with a start as something occurred to him.
    "You don't think he's in trouble down there, do you?" he said.
    "Who?" Rebecca asked as she rinsed out a saucepan.
    "Dad.