ReBecca put me on to this one, and I agree that this one is far more interesting than the non-geo 100 things (the fixation on Paris, as Callan noted, is weird). Others in on the fun are: Geotripper (the originator), Callan, and Hypocentre (among others).
I didn't limit myself to this year though (basically, I have seen my laptop this year and that is pretty much it, also I don't know if some of these happened in the past year see #95). The ones that happened in the past year are marked with an *, my comments are in (parenthesis) and italicized.
1. See an erupting volcano
2. See a glacier * (yep, see my Glacier National Park Photos series)
3. See an active geyser such as those in Yellowstone, New Zealand or the type locality of Iceland (years ago, which is sad because I am so close to Yellowstone right now)
4. Visit the Cretaceous/Tertiary (KT) Boundary. Possible locations include Gubbio, Italy, Stevns Klint, Denmark, the Red Deer River Valley near Drumheller, Alberta.* (I have lived with the KT for several years now. so I have visited it with every fiber of my being. Or you could just look at my profile picture)
5. Observe (from a safe distance) a river whose discharge is above bankful stage* (Poor York, it got Ouse-d. Sorry had to use the pun again. Here is the post)
6. Explore a limestone cave. Try Carlsbad Caverns in New Mexico, Lehman Caves in Great Basin National Park, or the caves of Kentucky or TAG (Tennessee, Alabama, and Georgia) (Lewis and Clark Caverns)
7. Tour an open pit mine, such as those in Butte, Montana, Bingham Canyon, Utah, Summitville, Colorado, Globe or Morenci, Arizona, or Chuquicamata, Chile.* (I wouldn't say a "tour" so much as visiting a platform above the Berkeley Pit, I might put the photos up at some point)
8. Explore a subsurface mine.* (Those Welsh were (are?) crazy. see my post on the mine, it is really impressive what people can do with hand tools, time, and a desire to not starve)
9. See an ophiolite, such as the ophiolite complex in Oman or the Troodos complex on the Island Cyprus (if on a budget, try the Coast Ranges or Klamath Mountains of California).
10. An anorthosite complex, such as those in Labrador, the Adirondacks, and Niger (there's some anorthosite in southern California too).
11. A slot canyon. Many of these amazing canyons are less than 3 feet wide and over 100 feet deep. They reside on the Colorado Plateau. Among the best are Antelope Canyon, Brimstone Canyon, Spooky Gulch and the Round Valley Draw.
12. Varves, whether you see the type section in Sweden or examples elsewhere.
13. An exfoliation dome, such as those in the Sierra Nevada.
14. A layered igneous intrusion, such as the Stillwater complex in Montana or the Skaergaard Complex in Eastern Greenland.
15. Coastlines along the leading and trailing edge of a tectonic plate (check out The Dynamic Earth - The Story of Plate Tectonics - an excellent website).
16. A ginkgo tree, which is the lone survivor of an ancient group of softwoods that covered much of the Northern Hemisphere in the Mesozoic.
17. Living and fossilized stromatolites* (Glacier National Park is a great place to see fossil stromatolites, while Shark Bay in Australia is the place to see living ones)
18. A field of glacial erratics
19. A caldera* (didn't see the geysers, but still visited Yellowstone)
20. A sand dune more than 200 feet high (Sand Dunes National Monument in CO, we swung by on a day-off during field camp, I don't know the official height, but they were plenty big).
21. A fjord
22. A recently formed fault scarp
23. A megabreccia
24. An actively accreting river delta
25. A natural bridge
26. A large sinkhole (one sunk the neighborhood burger joint where I was growing up, but that was years ago)
27. A glacial outwash plain
28. A sea stack
29. A house-sized glacial erratic
30. An underground lake or river
31. The continental divide * (I drove over it, it wasn't the purpose of the trip though)
32. Fluorescent and phosphorescent minerals * (common enough display at most museums, except Houston's museum has a computer simulation of it rather than the real thing. I was most confused by that)
33. Petrified trees* (had to find one for the science olympiad, so it wasn't found "in the wild")
34. Lava tubes
35. The Grand Canyon. All the way down. And back.
36. Meteor Crater, Arizona, also known as the Barringer Crater, to see an impact crater on a scale that is comprehensible (and it is quite BIG)
37. The Great Barrier Reef, northeastern Australia, to see the largest coral reef in the world.
38. The Bay of Fundy, New Brunswick and Nova Scotia, Canada, to see the highest tides in the world (up to 16m)
39. The Waterpocket Fold, Utah, to see well exposed folds on a massive scale.
40. The Banded Iron Formation, Michigan, to better appreciate the air you breathe.
41. The Snows of Kilimanjaro, Tanzania,
42. Lake Baikal, Siberia, to see the deepest lake in the world (1,620 m) with 20 percent of the Earth's fresh water.
43. Ayers Rock (known now by the Aboriginal name of Uluru), Australia. This inselberg of nearly vertical Precambrian strata is about 2.5 kilometers long and more than 350 meters high
44. Devil's Tower, northeastern Wyoming, to see a classic example of columnar jointing
45. The Alps.
46. Telescope Peak, in Death Valley National Park. From this spectacular summit you can look down onto the floor of Death Valley - 11,330 feet below.
47. The Li River, China, to see the fantastic tower karst that appears in much Chinese art
48. The Dalmation Coast of Croatia, to see the original Karst.
49. The Gorge of Bhagirathi, one of the sacred headwaters of the Ganges, in the Indian Himalayas, where the river flows from an ice tunnel beneath the Gangatori Glacier into a deep gorge.
50. The Goosenecks of the San Juan River, Utah, an impressive series of entrenched meanders.
51. (battle)shiprock, New Mexico, to see a large volcanic neck (sorry, had to modify this one, it isn't volcanic, but it was my favorite field area during field camp. I saw Red Dawn for the first time the other day, I was pleasantly surprised to see Battleship used as the backdrop for the scene against the three gunships)
52. Land's End, Cornwall, Great Britain, for fractured granites that have feldspar crystals bigger than your fist.
53. Tierra del Fuego, Chile and Argentina, to see the Straights of Magellan and the southernmost tip of South America.
54. Mount St. Helens, Washington, to see the results of recent explosive volcanism.
55. The Giant's Causeway and the Antrim Plateau, Northern Ireland, to see polygonally fractured basaltic flows.
56. The Great Rift Valley in Africa.
57. The Matterhorn, along the Swiss/Italian border, to see the classic "horn".
58. The Carolina Bays, along the Carolinian and Georgian coastal plain
59. The Mima Mounds near Olympia, Washington
60. Siccar Point, Berwickshire, Scotland, where James Hutton (the "father" of modern geology) observed the classic unconformity* (Indeed, but I want to go back when the landscape isn't as treacherously slippery. Read about it here.)
61. The moving rocks of Racetrack Playa in Death Valley
62. Yosemite Valley
63. Landscape Arch (or Delicate Arch) in Utah
64. The Burgess Shale in British Columbia - (only in hand sample and I guess that doesn't count)
65. The Channeled Scablands of central Washington
66. Bryce Canyon
67. Grand Prismatic Spring at Yellowstone
68. Monument Valley
69. The San Andreas fault
70. The dinosaur footprints in La Rioja, Spain
71. The volcanic landscapes of the Canary Islands
72. The Pyrennees Mountains
73. The Lime Caves at Karamea on the West Coast of New Zealand
74. Denali (an orogeny in progress)
75. A catastrophic mass wasting event* (does Quake Lake count, I didn't see it happen, but I see the results, There was also a mass wasting event up in a canyon not far from here that I got some video of, but that will wait until I figure out how to upload video).
76. The giant crossbeds visible at Zion National Park
77. The black sand beaches in Hawaii (or the green sand-olivine beaches)
78. Barton Springs in Texas
79. Hells Canyon in Idaho
80. The Black Canyon of the Gunnison in Colorado
81. The Tunguska Impact site in Siberia
82. Feel an earthquake with a magnitude greater than 5.0.
83. Find dinosaur footprints in situ*(shout out to MNHM)
84. Find a trilobite (or a dinosaur bone or any other fossil)
85. Find gold, however small the flake
86. Find a meteorite fragment
87. Experience a volcanic ashfall
88. Experience a sandstorm
89. See a tsunami
90. Witness a total solar eclipse ( I have in the past, I think it was 4th grade, but I wasn't near Nunnavat this year).
91. Witness a tornado firsthand.
92. Witness a meteor storm, a term used to describe a particularly intense (1000+ per minute) meteor shower *
93. View Saturn and its moons through a respectable telescope.* (I don't know about it being a respectable telescope, but I like it)
94. See the Aurora borealis, otherwise known as the northern lights.
95. View a great naked-eye comet, an opportunity which occurs only a few times per century
96. See a lunar eclipse* (And it was damn cold that night too, maybe I should post on that)
97. View a distant galaxy through a large telescope (back in my astronomy class we had access to the largest telescope in the state, Mars was also at its closest approach to Earth in quite a few years)
98. Experience a hurricane (we were passing through S. Carolina during one (except we stayed as far away as we could) it was like driving a submarine)
99. See noctilucent clouds
100. See the green flash
So this year I am a lowly 15/100 (maybe this is why thesis progress is seemingly slow). Overall I am 39.5/100 (boo...)