Join Dr. Alley and his team as they take you on "virtual tours" of National Parks and other locations that illustrate some of the key ideas and concepts being covered in Unit 11.
TECH NOTE - Click on the first thumbnail below to begin the slideshow. To proceed to the next image, move the mouse over the picture until the "next" and "previous" buttons appear ON the image or simply use the arrow keys.
Virtual Field Trip #1: Florissant Fossil Beds National Monument—Gnattily Dressed
Florissant Fossil Beds National Monument—Gnattily Dressed Photos by National Park Service (indicated) or R. Alley; this is the “Big Stump” fossil redwood.
The Colorado Rockies Front Range is folded up, perhaps from shallow-subduction drag.
West of the Front Range are the parks, occupying the low parts of the folds. This is the real South Park, viewed from Wilkerson Pass.
The real South Park seems to be a nicer place than the one on TV. Here, paintbrush bloom in the mountain air.
Near the east edge of South Park, Colorado is Florissant Fossil Beds National Monument, one of the little-visited “gems” of the National Park Service.
Fossil redwoods are among the highlights at the park. These, including the “Big Stump” (bottom, Natl. Park Service picture) are along the Petrified Forest Loop Trail.
“When the mountains are overthrown and the seas uplifted, the universe at Florissant flings itself against a gnat and preserves it.”-- Dr. Arthur C. Peale, Hayden Expedition Geologist, 1873 Fossil spider, bee, and leaf, Florissant (National Park Service Photos)
Fossil sumac (left) and hydrangea (right) leaves from Florissant.
The previous slides showed fossils of things slightly different from living types. You really need to put the old and new next to each other to see the changes. Here and in the next picture are a couple of the many, many examples. Modern whales evolved from a primitive group of hoofed mammals (top) into species that were progressively more adapted to life in the water (moving downward). Although not every step along the evolutionary path was fossilized, many transitional forms are known, and the progression is clear.
(left) Photographic collage showing evolution of life on Earth through the last 600 million years. The oldest fossils are at the bottom and youngest at the top. The size of each time interval is proportional to its duration; Proterozoic extends beyond 600 million years. (right) Fossils from the Mid-Atlantic States show change through time, from late Cretaceous (late Mesozoic, 6) to Pliocene (late Cenozoic, 1). The shape of the posterior (rear) end of these clams becomes more rounded in the younger species, and the area where the two shells are held together (ligamental cavity) gets larger.
Virtual Field Trip #2: Hardwoods—CAUSE and Park Paleontologist William Parker Explore the Petrified Forest
Hardwoods--CAUSE and Park Paleontologist William Parker Explore the Petrified Forest
CAUSE students, led by Paleontologist William Parker, hiking in Black Forest section of Petrified Forest National Park.
Many of the trees in the Petrified Forest were transported by rivers, losing their branches and often their bark before being buried and petrified. The conversion to stone was caused by the difference in chemistry between the trees themselves and groundwater in the volcanic-ash-rich soils, and is described in more detail in the Enrichment article in the textbook. This tree is
Araucarioxylon arizonicum, an extinct relative of modern monkey-puzzle trees. Over 200 types of fossil plants are known to be in the park.
A pile of petrified wood, Petrified Forest National Park. Most of the wood in the park was carried and buried in great floods.
Paleontologist William Parker shows the CAUSE film crew the “Alpha Stump”, in the Black Forest section of Petrified Forest National Park. Unlike most of the fossil trees in the park, the “Alpha Stump” is in place, its roots in the soil where it grew about 210 million years ago.
Insect burrows, probably the world’s oldest known fossil bee’s nest, in a petrified tree, Petrified Forest National Park.
Park Paleontologist William Parker (upper right) and ranger and UC-Berkeley graduate student Randall Irmis (left) excavating armor plates of late-Triassic (Mesozoic) giant-armored-amphibian
Koskinonodon, also called Buettneria, see far right), Petrified Forest National Park.
Paleontologist Randall Irmis shows CAUSE student Irene Meglis a still-sharp fossil tooth, Petrified Forest National Park.
Late Triassic (Mesozoic) fossil bone fragments, Petrified Forest. A simple field test--fossil bone sticks to your tongue, and fossil wood doesn’t.
Virtual Field Trip #3: Dinosaurs: Where They Lived, and How They Died
The Green River in Dinosaur National Monument Photos by R. Alley or as indicated.
The river-channel and floodplain deposits of the Jurassic (mid-Mesozoic, about 150 million years old) Morrison Formation of Dinosaur National Monument, Colorado and Utah, were tipped up after being hardened.
The Quarry at Dinosaur Ledge. Eleven types of dinosaurs were washed onto this sand bar, perhaps in a great flood, buried, and their bones replaced by silica from groundwaters. The living types are quite different from their older relatives at Petrified Forest; a lot of evolutionary changes have occurred during the intervening 60 million years.
Four views of the Quarry at Dinosaur Ledge. Ranger in lower left for scale. Some of those dinosaurs were big!
The 49,000-year-old, 0.7-mile-across Barringer Impact Crater of Arizona was made by a rather small meteorite, roughly 150 feet (50 m) across--tiny compared to the one that killed the dinosaurs. Notice the road on the right for scale.
Top Left: Gravity field of Chicxulub impact crater--the meteorite that killed the dinosaurs, on the Yucatan Peninsula. The crater is buried under younger rocks, but is quite evident here. The circular crater, between the pink arrows, is about 110 miles across. Top Right: Impact breccia. When a meteorite hits, it breaks rocks. This core is from the Manson, Iowa impact structure. Above: Shocked quartz from a meteorite impact. The bright colors are from the view between polarizing filters; the crossing lines are impact features. The grain is roughly 1/10 inch across.
(Left) 1/250 in (0.1 mm) diameter cosmic spherule from the moon. Spherules such as this are well-known to result from impact deposits, and are found in the special K/T impact bed that marks the end of the dinosaurs. (Right) The finger is pointing to the K/T boundary bed marking the end of the dinosaurs, at Big Bend National Park.
Virtual Field Trip #4: Dinosaurs: What They Stepped In
Dinosaurs: What They Stepped In, A Virtual Tour of Dinosaur Ridge All pictures in this show are by Dr. Alley unless noted; some of the pictures here feature PSU graduate and noted scientist Matt Spencer.
Dinosaur Ridge, just west of Denver, Colorado, is part of the Morrison Fossil Area National Natural Landmark as designated by the National Park Service. In the Cretaceous Period of the Mesozoic Era, about 100 million years ago, the area that is now the Ridge sat on the edge of the great Interior Seaway that extended eastward across Kansas, and connected the Gulf of Mexico with the Arctic Ocean. Sediments were deposited, hardened and then tipped up (picture at right) as the Rockies were raised just to the west. The dinosaur trackway (lower right) is the big attraction at the Ridge, although there is quite a bit more to see (including modern rabbits).
The dinosaur tracks really are spectacular. Various dinosaurs walked across the muddy surface, probably heading for a water hole. The little sign (bottom of the picture on the left) points to a three-toed
Ornithomimus track. A picture of one of the larger Iguanodon tracks is shown in the inset, with kids’ hands for scale [from the Friends of Dinosaur Ridge website http://www.dinoridge.org/gallery/full36.html]
Shown here are various animal burrows from a shallow-water deposit near the dinosaur trackways (with an interpretive sign to give you an idea of the scale). Modern muds similar to these are commonly burrowed by creatures looking for food or avoiding enemies. After a mud layer is deposited, it usually takes a while for the mud to stabilize, and critters to move in and burrow the heck out of the mud, as seen here.
A careful examination of the burrowed rocks from the previous picture shows that various critters were stirring the mud, including big ones (pink arrow) and little ones (blue arrow). Not every layer gets burrowed--if there is too little oxygen to support critters, or too little for critters to eat, or the layer is buried too rapidly, then burrowing may be restricted or absent. Here, the heavily burrowed layer (far right, green arrow) is buried under a moderately burrowed layer covered with ripple marks (the two red arrows in the upper left of the picture point along ripple-mark crests). In turn, the rippled layer was buried by another layer, which was buried by another… (see next slide).
The previous slide showed a burrowed layer buried beneath a rippled layer. Here, a different rippled layer was covered up by yet another rippled layer. (If you don’t see it, the next slide adds some annotations to help.)
In case you didn’t see the features in the previous slide, the solid pink line divides the layer on the bottom (which in the picture is to the upper right) from the layer on top (which in the picture is to the lower left). The crests of two ripples on the layer on the bottom are marked by the light-blue dot-dash lines, and the crests of five ripples on the layer on the top are marked by the dark-blue dotted lines.
As interesting as ripples and burrows may be, most people go to Dinosaur Ridge to see dinosaur tracks.
And, here are a few more pictures of the main trackway at Dinosaur Ridge. Many more trackways have been reported along the Front Range near Denver, and there are other tracks at Dinosaur Ridge in other rock layers (some coming later in this show), but this is the easiest one to see.
Here are a couple more interesting items at Dinosaur Ridge. On the left is a dinosaur bone, still in the rock (lens cap for scale). Above, the yellow-orange-ish layer is volcanic ash, from a very large eruption nearby, which is sandwiched between more-ordinary sedimentary rocks.
On the other side of Dinosaur Ridge from the “main” trackway seen earlier, you can see dinosaur tracks edge-on, such as this one indicated by Dr. Alley. The next picture includes an outline of the track.
“Artistic” rendition of dinosaur pulling foot out of mud after making track at Dinosaur Ridge, near Denver.
Matt Spencer with dinosaur track, Dinosaur Ridge, near Denver. The next picture is a close-up with this track outlined.
Close-up of previous picture, with dinosaur track outlined.
Dinosaurs didn’t walk on the ceiling. We just turned the previous picture upside-down, but if you found a track this way in nature, you should conclude that the rock has been turned upside-down.
A long and fascinating story links the dinosaurs tromping on mud when Denver was a coastal city, and this mountain goat looking down toward Denver from Mt. Evans 65 million years later. The giant meteorite that killed the dinosaurs left their “jobs” open to others, and evolution filled those jobs with the creatures we now know and enjoy.
Want to see more?
Here are some
optional vTrips you might also want to explore! (No, these won't be on the quiz!)
Dinosaur National Monument
(Provided by UCGS)