Although rocks are broadly classified as either sedimentary, igneous, or metamorphic, sometimes these classes are not so clear. As with any natural system, there may be gray areas, such as in the following rock texture. This is an igneous rock, but it has most of the hallmarks of a metamorphic rock. How is this possible?

Here are two more pictures. Minerals viewed under a polarizing light microscope are aesthetically pleasing just for their own sake. Petrographic examination also yields important information regarding mineral identification and textures of rock fabric. Some rocks are stronger than others because of the way the grain or crystal boundaries interlock. This can have a significant influence on compressive strength, abrasiveness, and cutting or boring difficulty. Some minerals also cause premature degradation of cement and concrete.

Several of the rocks shown here are from the northern Sierras, which oddly enough drew me back under quite different circumstances over the years.

Across the High Sierra
I have always enjoyed long road trips across the country, perhaps because they have all the elements of a Homeric adventure. After completing basic training for the Army, I was ready for assignment to my permanent duty station. I was directed to travel from Norfolk, Virginia to Monterrey, California, so I flew home to Wisconsin and prepared to drive the rest of the way. My 1964 Dodge Polara had been purchased for $125 during my last year in high school, and I naively anticipated the adventure of driving nearly 2,500 miles across the continent. As I crossed the Minnesota border early on the first morning out, it occurred to me that I had just driven the farthest distance of my entire life. This was also to be my first time completely alone, and I savored the thought of the next week spent on the open road.

I picked up the small state highway to Northfield, reportedly the scene of Jesse James’ last, abortive raid, and then left the winding, picturesque Minnesota country roads behind in favor of I-35 South. The Slant-6 engine rattled along, and the speedometer needle floated near 55. I wanted to avoid placing too great a burden on the 23-year old car, which had compiled an indeterminate number of miles during its lifetime. It was the month of March, and as I rolled south through Minnesota and into Iowa, the snow banks shrank and the gray, lowering clouds threatened rain rather than snow. Finally turning west at Des Moines onto I-80, the stiff north wind buffeted the Dodge sideways, and a motorcycle passed, canted nearly 30 degrees into the wind to maintain equilibrium. It felt like a point of no return, and my only course was west toward on unknown shore. All across the brown, late Winter, windblown prairie I gripped the wide, heavy plastic steering wheel, fighting the wind and an out-of-balance front wheel that set up a harmonic shaking throughout the car. I anxiously scrutinized the instrument cluster until reaching Lincoln, Nebraska, where I decided to stop for the day after successfully entering yet another state for the first time in my life. Due to my lack of firsthand knowledge of the country’s geography, I imagined that as I approached central Nebraska, I would soon descend into a vast desert. This thought prompted me to stop in Kearney to have the increasingly maddening vibration repaired, and after having the wheel balanced, I was off again. Nebraska seemed like such a long state, and I had taken to peering at my instrument cluster again, worriedly watching the alternator needle as it leaned slightly over to "discharge". Tapwater from the motel near the outskirts of Cheyenne seemed to rejuvenate the battery.

It felt as though I rolled endlessly across the plains of Nebraska, and had plenty of time to marvel at the early pioneers who encountered the vast expanses of rolling grasslands for weeks on end. Wyoming was different from anything that I had ever seen, and I was excited to cross even the low, rugged hills that represent the beginning of the Rocky Mountains in this area. The low hills were soon gone, and I was on a scrub desert. Gradually, through the thickening gloom, I discerned a more prominent range of the Rockies, and felt a thrill to have reached tangible evidence that I was actually Out West! Black, snow-filled clouds released flurries of stinging white crystals until it became difficult to see. I crept through the deepening gloom, now at only 40 mph, peering just beyond the dim circle of light cast by my weakened headlights. Nervous glances at the worrisome alternator gauge revealed no information, and I crept on until the glowing oasis of the Little America truck stop came in view. I opened the driver’s door into a biting gale of wet, swirling snow that turned the bright parking lot lamps of the gas station into hazy sundogs. A glance at my headlights revealed that two inches of frozen snow had accumulated over the lenses, diffusing the bulbs’ rays into a feeble orange glow. The work of ten minutes chipping ice with a screwdriver was sufficient to restore them to their former brilliance, and reduce my hands to numbness. After a late dinner of hot roast beef and mashed potatoes, smothered in thick, rich gravy, I was prepared to resume driving, my spirits buoyed by a good meal and the restoration of my headlights. The dashboard instrument lights fluoresced a soft green through hollow push button controls, as I followed the dual beam headlights through the slackening storm. I stopped in Bridger for the night, and was struck by the sharp cold and clear, prairie quiet in which the calls of coyotes drifted across the darkness.

The next day, at last I encountered the long-expected desert, with the descent into Utah and the Great Salt Lake basin. What an amazing site from this ribbon of blacktop, where salt and white mud stretch off into the distance, an apparent sea of white in which the hazy images of distant mountain peaks floated and bobbed. Whirling storms of salt danced across the road, and I noted the custom of passersby to spell their initials with cobbles tossed in the salt mud. I hoped that the end of this day would see me in California at last, and toward the late afternoon, I passed Reno, dominated by the brightly colored Circus-Circus. Although exhausted, I sensed that I was close to the day’s goal as the grade of the road increased and jagged shoulders of rock encroached on the interstate. Past the last of the garishly flashing State Line casinos, a gorgeous, knife-edged valley came into view, with steep slopes nearly obscured by snow-covered, majestic pines. The interstate clung to the side of the valley, and the narrow lanes allowed only momentary lapses in concentration to enjoy the postcard view of the opposite slope.

The narrow lanes, sharp curves, and momentary night-blindness from the continuous glare of oncoming headlights began to tax my tired nerves. I pulled off the interstate at Truckee, which seemed as exciting as a Swiss playground in a Roger Moore-era James Bond movie due to the heavy fall of snow and abundance of ski rack-equipped vehicles. I found a motel, and rented a cabin, falling asleep satisfied that I had at least reached California. The following morning, the bottom half of the front fender succumbed to two thousand miles of vibration, as it collapsed in a crumble of rust and Bond-o. I proceeded west on I-80, over the summit of the Sierras, and began the gradual descent though snow-covered firs and past large warning signs apparently written in trucker language, advising them to "better let ‘er drift". The snow disappeared, as did the firs, to be replaced by lush fields and humid warmth of the fertile valley. I had successfully crossed the Great Plains, salt desert, and Nevada wasteland, and my object was finally in reach.

After spending the night in Monterrey, I headed for Fort Ord where I would report for duty. This epic journey across the Sierras represented a significant step away from my small home-town, which to me was nothing but a dead end where I could expect only to become an obscure loser. But here was a chance for a new beginning, following the same route as others who came west to improve their fortunes. As I passed beneath the arched sign that boldly proclaimed "Fort Ord, 7th Infantry Division (Light)", I sensed the freedom that I had enjoyed on the open road slip away. However, the self- direction and sense of adventure that I had experienced while crossing the continent would reassert themselves in time.


Hell-Roaring Creek
The first Summer that I lived in Colorado provided me with an opportunity to do some field work in the western Rocky Mountains. To reach my first campsite, I followed a rutted dirt road along the bank of Hell Roaring Creek, and found a rocky path that led to an abandoned mine. A cold, mountain stream gurgled and murmured within its narrow banks, at the bottom of a narrow defile carved by furious erosion to expose towering, jagged cliffs of maroon sandstone on one side, and a more gently sloping mass of granite on the other. By early afternoon, the maroon hills were softened by shadow, too steep to allow even the high Colorado sun to fully illuminate the bottom of the miniature gorge. I unfolded my double-burner Coleman stove, and placed it carefully on the hood. As the twin burners hissed bright blue heat, searing mixed vegetables on one side and Dinty Moore on the other, I watched swallows dart after insects against the backdrop of the waning Rocky Mountain sunset. I basked, self satisfied, in the sounds of the gurgling creek, the ever softening sunlight, lengthening shadows, and lilting, cool breeze. As dusk encroached, I settled in by flashlight with a Stephen King novel. I read, mesmerized as rain pattered on the roof and lightning flashed, momentarily revealing the churning mass of foliage around me and briefly illuminating the high cliffs, now turned blood-black.

I awoke to quiet. But hadn’t there been something, some slight noise? Yes, a rustling from the darkness. Now a gentle scraping, a hollow rasping as something brushed the truck’s aluminum running board not two feet from where I lay. I stirred into a sitting position in preparation for daring to look upon the axe-wielding, vacant-eyed, shuffling menace who undoubtedly stood poised outside. There was nothing. Dismissing the episode, I slept fitfully until the bright, early morning Rocky Mountain sunrise awoke me. The following night, again I awoke to the sound of a scraping, hollow rasp coming from the direction of my truck. Surely this was not my imagination. With flashlight in hand, I peered into the gloom in time to see a low, loping shadow bound away. No axe-murdering fiend, but only a harmless animal! My mind at ease, I dropped off to sleep.

After returning to camp at the end of a long day, during which the circling vultures seemed to take more than a passing interest, my thoughts were only of rest. Again just after dark, a scraping, rustling sound emanated from beneath my truck. I raced the short distance to my vehicle, and a giant porcupine rocketed from underneath. In the morning, I began to wonder why a porcupine would show so much interest in visiting my truck every evening. The idea nagged at me, finally arousing my curiosity to the point where I had to crawl underneath and determine for myself what fascinations the undercarriage of a 1985 Dodge Ramcharger could hold. My amusement of the previous night quickly turned to shock as I saw the frayed, inner cording of the lower radiator hose, exposed where the rubber coating had been gnawed away. Similarly, the rubber connecting hose between the steel transmission cooling lines and the radiator had been gnawed to the inner wall. All three fall belts had been gnawed through to expose the thin steel wires. This was not quite so funny, and I suddenly was forced to consider myself in a potentially serious situation, facing the prospect of being stranded in the middle of nowhere.

The fourth night, as dusk approached, I sat with the window rolled down, waiting. After three nights in a row, would the porcupine pursue his apparently insatiable lust for rubber? I was a trespasser in his territory, but I had my own goals to achieve. Although not a charging grizzly, he had already demonstrated the capacity to leave me stranded in the wilderness. I wasn’t entirely pleased with what I was contemplating because after all, the pistol was intended only for last ditch defense, the four-inch barrel designed for a point-blank deterrent against in-your-face aggression, of either the four-legged or two-legged variety. I waited for dark. Then, movement from the bushes as the giant porcupine slowly ambled into view. I gently shifted the revolver into my right hand, my fingers pressing the rough-textured rubber grip into my palm. My left hand curled around my right in a gentle caress. With my head motionless, and stare slightly averted from my prey, I slowly brought both arms up and out in a locked, extended position, aligning the short barrel roughly on the center-of-mass of the porcupine out of the corner of my eye. With the trigger slightly depressed, my thumb found the gnurled, rough surface of the hammer and silently locked it to the rear. My eyes shifted along the length of the barrel, aligning the sights. I began the slow squeeze that would send the hammer hurtling forward on its short, inexorable course.

The thunderous blast of the .44 Magnum exploded off the cliffs a split second before I felt the familiar sensation of a fastball slamming home into my palm. As my eyes adjusted to peer through the smoke and gloom, I saw the porcupine scrambling back up the path, perhaps the first time in his long dominion over this meadow that he had ever had to scramble. No, I wouldn’t leave a wounded animal, nor would I repeat this debacle night after night. I leapt from the truck and raced up the short, steep hill, feet scrabbling for purchase on the loose, gravelly soil. As I turned onto the path, there was the porcupine, moving with amazing speed. I bolted after him, too close to miss, my heart pounding with a mixture of blood lust and a desire to make an end of this awful task. Another blast, like dynamite within the confines of the narrow gorge, and the .44 belched smoke and flame enough for a line of musket-firing dragoons. Quills flew and the porcupine dropped, twitching and spent. One final blast for the coup de grace. I derived no enjoyment from the destruction of such a creature, whose only sin had been an unnatural craving for rubber, unfortunately at my expense, and ultimately his own.

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