**Table 1.\--Locations, elevations, dates of occurrence, and
descriptions of profiled spring season landslides, Colorado and
Wyoming.**

+-------------+-------------+---------------+------------------------+
| **          | **          | **DATE OF     | **DESCRIPTION/SOURCE   |
| LANDSLIDE** | LOCATION/** | OCCURRENCE**  | OF INFORMATION1**      |
|             |             |               |                        |
| **EVENT     | **          |               |                        |
| NO.**       | ELEVATION** |               |                        |
+-------------+-------------+---------------+------------------------+
| 1           | Approx. 7   | Initial       | I conducted a detailed |
|             | mi. south   | movement in   | study of this          |
|             | of          | 1977 occurred | pre-existing landslide |
|             | Sheridan,   | between April | 1977 and 1978. It is a |
|             | Wyoming; T. | 2nd and April | shallow translational  |
|             | 54 N., R.   | 15th          | slide/earthflow in     |
|             | 83 W., NW   |               | weathered,             |
|             | 1/4 of SW   |               | Tertiary-age           |
|             | 1/4 of      |               | sedimentary deposits.  |
|             | Section 6/  |               | Borehole inclinometer  |
|             | 4460 ft.    |               | measurements revealed  |
|             |             |               | that initial movement  |
|             |             |               | in 1977 occurred       |
|             |             |               | sometime between April |
|             |             |               | 2nd and April 15th,    |
|             |             |               | During that period, 1  |
|             |             |               | to 2 m of drifted snow |
|             |             |               | that covered the slide |
|             |             |               | melted (Chleborad,     |
|             |             |               | 1980).                 |
+-------------+-------------+---------------+------------------------+
| 2           | do.         | Initial       | Borehole inclinometer  |
|             |             | movement in   | measurements made in   |
|             |             | 1978 occurred | 1978 indicate initial  |
|             |             | between March | movement of the        |
|             |             | 24th and      | landslide described    |
|             |             | April 4th.    | above occurred         |
|             |             |               | sometime between March |
|             |             |               | 24, and April 4. On    |
|             |             |               | March 13th, 1978 the   |
|             |             |               | slide was covered with |
|             |             |               | approximately 1.5 m of |
|             |             |               | drifted snow. By April |
|             |             |               | 4th all the snow had   |
|             |             |               | melted (Chleborad,     |
|             |             |               | 1980).                 |
+-------------+-------------+---------------+------------------------+
| 3           | Mesa Verde  | April 18th or | \"A motorist yesterday |
|             | National    | 19th, 1979    | \[April 19th\] used    |
|             | Park, 9     |               | his CB to radio for    |
|             | miles ESE   |               | help after being       |
|             | of Cortez,  |               | trapped by a slide on  |
|             | Colorado;   |               | the entrance road \[to |
|             |             |               | Mesa Verde National    |
|             | T. 35 N.,   |               | Park.\" (Montezuma     |
|             | R. 14 W., S |               | Valley Journal,        |
|             | 1/2 of      |               | 4/20/79, p. 1).        |
|             | Sect. 5/    |               |                        |
|             |             |               |                        |
|             | 7850 ft.    |               |                        |
+-------------+-------------+---------------+------------------------+
| 4           | do.         | April 29th,   | \[Photo caption\]      |
|             |             | 1979          | \"\...A slide Sunday   |
|             |             |               | morning \[April 29th\] |
|             |             |               | brought down an        |
|             |             |               | estimated 2,500 cubic  |
|             |             |               | yards of material      |
|             |             |               | which was cleared      |
|             |             |               | enough to open a lane  |
|             |             |               | \[of the entrance road |
|             |             |               | to Mesa Verde National |
|             |             |               | Park\].\" (Montezuma   |
|             |             |               | Valley Journal,        |
|             |             |               | 5/2/79, p. 1).         |
+-------------+-------------+---------------+------------------------+
| 5           | do.         | April 30th,   | \[Photo caption\] \"On |
|             |             | 1979          | Monday morning \[April |
|             |             |               | 30th\], a massive      |
|             |             |               | slide of an estimated  |
|             |             |               | 150,000 cubic yards    |
|             |             |               | sealed the road        |
|             |             |               | \[entrance road to     |
|             |             |               | Mesa Verde National    |
|             |             |               | Park\] again.\"        |
|             |             |               | (Montezuma Valley      |
|             |             |               | Journal, 5/2/79, p.    |
|             |             |               | 1).                    |
+-------------+-------------+---------------+------------------------+
| **          | **          | **DATE OF     | **DESCRIPTION/SOURCE   |
| LANDSLIDE** | LOCATION/** | OCCURRENCE**  | OF INFORMATION1**      |
|             |             |               |                        |
| **EVENT     | **          |               |                        |
| NO.**       | ELEVATION** |               |                        |
+-------------+-------------+---------------+------------------------+
| 6           | Steamboat   | Between April | \"Mud slides damage    |
|             | Springs,    | 29th and May  | ski jumps\--Mud season |
|             | Colorado;   | 13th, 1982    | has been particularly  |
|             | T.6 N.,     |               | harsh on the Howelsen  |
|             |             |               | Hill ski jumps. Heavy  |
|             | R. 84 W.,   |               | snow melt has caused   |
|             | SW 1/4 of   |               | tons of earth to slide |
|             | NW 1/4 of   |               | off both the 70 m and  |
|             | Sect. 6/    |               | 90 m jumps\....Several |
|             |             |               | feet of earth          |
|             | 6900 ft.    |               | saturated with melted  |
|             |             |               | snow broke loose       |
|             |             |               | beneath a concrete     |
|             |             |               | retaining wall just    |
|             |             |               | under the crown of the |
|             |             |               | hill. The mud slid     |
|             |             |               | down the landing area  |
|             |             |               | of the jump, carrying  |
|             |             |               | with it wooden         |
|             |             |               | framework and steel    |
|             |             |               | reinforcing bars\...\" |
|             |             |               | (Steamboat Pilot,      |
|             |             |               | 5/13/82, p. 1).        |
+-------------+-------------+---------------+------------------------+
| 7           | Approx. 3   | May 21st,     | \"See Me, see          |
|             | mi SE of    | 1982          | mudslide\--With a      |
|             | Steamboat   |               | noise that one witness |
|             | Springs,    |               | described as           |
|             | Colorado;   |               | thunderous, tons of    |
|             | T. 6 N.,    |               | mud slid from the      |
|             |             |               | lower portion of the   |
|             | R. 84 W.,   |               | Steamboat Ski Areas    |
|             | NE 1/4 of   |               | See Me run last Friday |
|             |             |               | night\[May             |
|             | NE 1/4,     |               | 21st\]\...The slide    |
|             | Sect. 27/   |               | left a fracture line   |
|             |             |               | 10-12 feet deep        |
|             | 7500 ft.    |               | according to Mountain  |
|             |             |               | Manager Loris          |
|             |             |               | Werner\....Friday      |
|             |             |               | night\'s slide left a  |
|             |             |               | river of mud that      |
|             |             |               | stretched hundreds of  |
|             |             |               | yards to a small creek |
|             |             |               | adjacent to Mt. Werner |
|             |             |               | road.\" (Steamboat     |
|             |             |               | Pilot, 5/27/82, p. 1)  |
+-------------+-------------+---------------+------------------------+
| 8           | Approx. 5   | May 27th,     | \"Redstone mud scare   |
|             | mi NW of    | 1983          | causes evacuation of   |
|             | Redstone,   |               | valley                 |
|             | Colorado;   |               | residents\--Their      |
|             |             |               | homes and safety       |
|             | T. 10 S.,   |               | endangered by the      |
|             | R. 89 W.,   |               | threat of a buildup of |
|             |             |               | water behind a         |
|             | SW 1/4 of   |               | mudslide in Coal       |
|             | Sect. 11/   |               | Creek, residents in    |
|             |             |               | low-lying areas of the |
|             | 8900 ft.    |               | Crystal River Valley   |
|             |             |               | were evacuated Friday  |
|             |             |               | by emergency crews.    |
|             |             |               | According to Pitkin    |
|             |             |               | County Undersheriff    |
|             |             |               | Don Davis, melt water  |
|             |             |               | from the exceptionally |
|             |             |               | deep snowpack \"had    |
|             |             |               | saturated everything\" |
|             |             |               | and a sudden mudflow   |
|             |             |               | Friday afternoon       |
|             |             |               |                        |
|             |             |               | \[May 27th\] blocked   |
|             |             |               | Coal Creek with a mud  |
|             |             |               | plug some 35 feet wide |
|             |             |               | and 25 feet high. The  |
|             |             |               | mud flowed from Gold   |
|             |             |               | Camp Canyon into Coal  |
|             |             |               | Creek which feeds into |
|             |             |               | the Crystal River at   |
|             |             |               | Redstone in Pitkin     |
|             |             |               | County\...\" (Aspen    |
|             |             |               | Times, 6/2/83, p. 10). |
+-------------+-------------+---------------+------------------------+
| **          | **          | **DATE OF     | **DESCRIPTION/SOURCE   |
| LANDSLIDE** | LOCATION/** | OCCURRENCE**  | OF INFORMATION1**      |
|             |             |               |                        |
| **EVENT     | **          |               |                        |
| NO.**       | ELEVATION** |               |                        |
+-------------+-------------+---------------+------------------------+
| 9           | Steamboat   | May 12th,     | \"\...On Saturday      |
|             | Springs,    | 1984          | night \[May 12th\] a   |
|             | Colorado;   |               | mudslide changed the   |
|             | T. 6 N.,    |               | course of Butcherknife |
|             |             |               | Creek at the end of    |
|             | R. 84 W.,   |               | Hill St.\" (Steamboat  |
|             | SE 1/4 of   |               | Pilot, 5/17/84, p. 1)  |
|             | SE 1/4 of   |               |                        |
|             | Sect. 8/    |               |                        |
|             |             |               |                        |
|             | 6800 ft.    |               |                        |
+-------------+-------------+---------------+------------------------+
| 10          | Approx. 7   | May 13th,     | \"Woman dies in mud    |
|             | miles SW of | 1984          | slide; melting snow    |
|             | Telluride,  |               | wrecks county          |
|             | Colorado/   |               | roads\--A 24-year old  |
|             | 9600 ft.    |               | woman student at       |
|             |             |               | Western State College  |
|             |             |               | in Gunnison died a     |
|             |             |               | gruesome death after   |
|             |             |               | the car she and a      |
|             |             |               | friend were driving    |
|             |             |               | back to school washed  |
|             |             |               | off Highway 145 near   |
|             |             |               | Trout Lake Sunday      |
|             |             |               | \[May 13th\] afternoon |
|             |             |               | and tumbled about 150  |
|             |             |               | feet before coming to  |
|             |             |               | rest upside down in    |
|             |             |               | the mud.\" (Telluride  |
|             |             |               | Times, 5/17/84, p. 1)  |
+-------------+-------------+---------------+------------------------+
| 11          | Approx. 2   | May 14th,     | \"Rising waters flood  |
|             | mi. north   | 1984          | Route County\--As of   |
|             | of Oak      |               | Tuesday afternoon      |
|             | Creek,      |               | \[May 15th\], flood    |
|             | Colorado;   |               | waters and/or          |
|             |             |               | mudslides had          |
|             | T. 4 N., R. |               | temporarily closed     |
|             | 85 W.,      |               | portions of numerous   |
|             |             |               | County roads\...A      |
|             | NE 1/4 of   |               | 75-foot section of     |
|             | SE 1/4 of   |               | Colorado 131 slid      |
|             | Sect. 19/   |               | Monday \[May 14th\],   |
|             |             |               | 14 miles south of its  |
|             | 7300 ft.    |               | junction with U.S.     |
|             |             |               | 40\...\" (Steamboat    |
|             |             |               | Pilot, 5/17/84, p. 1)  |
+-------------+-------------+---------------+------------------------+
| 12          | Approx. 4   | June 1st,     | \"Mudslide blocks Blue |
|             | mi. north   | 1984          | River\--\...the        |
|             | of          |               | mudslide occurred on   |
|             | Si          |               | the night of Friday    |
|             | lverthorne, |               | June 1st on the east   |
|             | Colorado;   |               | side of the Blue River |
|             | T. 4 S., R. |               | 4 miles north of       |
|             | 78 W., NE   |               | Silverthorne.\"        |
|             | 1/4 of SW   |               | (Summit County         |
|             | 1/4 of      |               | Journal, 6/14/84, p.   |
|             | Sect. 23/   |               | 3)                     |
|             |             |               |                        |
|             | 8800 ft.    |               |                        |
+-------------+-------------+---------------+------------------------+
| **          | **          | **DATE OF     | **DESCRIPTION/SOURCE   |
| LANDSLIDE** | LOCATION/** | OCCURRENCE**  | OF INFORMATION1**      |
|             |             |               |                        |
| **EVENT     | **          |               |                        |
| NO.**       | ELEVATION** |               |                        |
+-------------+-------------+---------------+------------------------+
| 13          | Between     | April 16th,   | \"As a result of a     |
|             | Granby and  | 1985          | small landslide        |
|             | Tabernash,  |               | beneath the track,     |
|             | Colorado/   |               | Amtrak\'s eastbound    |
|             |             |               | 14-car California      |
|             | 8160 ft.    |               | Zephyr passenger train |
|             |             |               | was derailed in the    |
|             |             |               | Fraser River canyon,   |
|             |             |               | Colorado, between the  |
|             |             |               | towns of Granby and    |
|             |             |               | Tabernash, on April    |
|             |             |               | 16, 1985. Fortunately, |
|             |             |               | no one was killed in   |
|             |             |               | the spectacular        |
|             |             |               | accident; however, 26  |
|             |             |               | people were injured,   |
|             |             |               | and damages totaled    |
|             |             |               | about \$3.5 million    |
|             |             |               | (Schuster, 1986).      |
+-------------+-------------+---------------+------------------------+
| 14          | Approx. 20  | April 24th,   | The Roan Creek         |
|             | mi. NW of   | 1985          | landslide is a         |
|             | DeBeque,    |               | slump-earthflow        |
|             | Colorado.   |               | complex. It is located |
|             |             |               | in the Roan Creek      |
|             | T. 6 S., R. |               | drainage basin in      |
|             | 99 W.,      |               | Garfield County,       |
|             | Section 28  |               | Colorado on the        |
|             | and 33/     |               | north-facing slope of  |
|             |             |               | Kimball Mountain. It   |
|             | 6400 ft.    |               | initially failed on 24 |
|             |             |               | April 1985 (Umstot,    |
|             |             |               | 1989).                 |
+-------------+-------------+---------------+------------------------+
| 15          | Approx. 5   | April 30th,   | \"Starting at          |
|             | mi. West of | 1987          | approximately 8:30     |
|             |             |               | p.m. on April 30,      |
|             | Telluride,  |               | 1987, a series of      |
|             | Colorado/   |               | landslides occurred in |
|             |             |               | a pre-existing         |
|             | 9000 ft.    |               | landslide source area  |
|             |             |               | located along the      |
|             |             |               | upper edge of Deep     |
|             |             |               | Creek Mesa. As the     |
|             |             |               | landslides moved over  |
|             |             |               | the edge of the mesa   |
|             |             |               | and through a narrow   |
|             |             |               | notch in the sandstone |
|             |             |               | rim, they mobilized    |
|             |             |               | into debris flows. The |
|             |             |               | debris flows then      |
|             |             |               | traveled 2200 ft over  |
|             |             |               | slopes of              |
|             |             |               | approximately 50% (a   |
|             |             |               | vertical drop of 960   |
|             |             |               | ft) into the valley of |
|             |             |               | the San Miguel River.  |
|             |             |               | The debris flows       |
|             |             |               | crossed State Highway  |
|             |             |               | 145 at a point 700 ft  |
|             |             |               | upslope from the       |
|             |             |               | valley                 |
|             |             |               | floor\.....Damage      |
|             |             |               | estimates for Animas   |
|             |             |               | Aggregate are on the   |
|             |             |               | order \$1.5 million,   |
|             |             |               | and airport design     |
|             |             |               | consultant Greg Isbill |
|             |             |               | gave the Telluride     |
|             |             |               | Airport Authority an   |
|             |             |               | estimate of \$250,000  |
|             |             |               | to \$500,000 to repair |
|             |             |               | the landslide scar     |
|             |             |               | area.\" (Stover and    |
|             |             |               | others, 1987)          |
+-------------+-------------+---------------+------------------------+
| 16          | Approx 1    | Between April | \[Photo Caption\]      |
|             | mile east   | 29th and      | \"Lingering snowpack   |
|             | of          |               | in the mountains above |
|             | Steamboat   | May 5th,      | Steamboat Springs mean |
|             | Springs,    | 1993.         | this recent mudslide   |
|             | Colorado/   |               | across Spring Creek    |
|             |             |               | Road isn\'t likely to  |
|             | 7000 ft.    |               | be the last one of the |
|             |             |               | spring.\" (Steamboat   |
|             |             |               | Pilot, 5/6/93, p. 8B). |
+-------------+-------------+---------------+------------------------+
| 17          | Approx. 3   | May 19th or   | \"Mud slides down runs |
|             | mi SE of    | 20th, 1993    | at ski area\--Super    |
|             | Steamboat   |               | saturated soil         |
|             | Springs,    |               | conditions triggered a |
|             | Colorado/   |               | huge mudslide at the   |
|             |             |               | Steamboat ski area     |
|             | 8200 ft.    |               | last week. The slide   |
|             |             |               | started just below     |
|             |             |               | Betwixt Catwalk in a   |
|             |             |               | wooded area. It        |
|             |             |               | continued through the  |
|             |             |               | trees until it came to |
|             |             |               | Lower Concentration    |
|             |             |               | \[ski run\], then it   |
|             |             |               | turned and followed    |
|             |             |               | the run down the hill. |
|             |             |               | It wound its way to    |
|             |             |               | the base of            |
|             |             |               | Thunderhead lift       |
|             |             |               | before dying out. The  |
|             |             |               | slide apparently       |
|             |             |               | occurred late last     |
|             |             |               | Wednesday \[May 19th\] |
|             |             |               | or early Thursday      |
|             |             |               | morning \[May 20th\].  |
|             |             |               | It was discovered by   |
|             |             |               | ski area               |
|             |             |               | security\....Ken       |
|             |             |               | Kowynia, Lands         |
|             |             |               | Forester with Route    |
|             |             |               | National Forest said   |
|             |             |               | it was probably caused |
|             |             |               | by \'super-saturated   |
|             |             |               | soil conditions\' that |
|             |             |               | resulted from heavy    |
|             |             |               | winter snows and were  |
|             |             |               | exacerbated by last    |
|             |             |               | week\'s severe         |
|             |             |               | rainstorms.\"          |
|             |             |               | (Steamboat Pilot,      |
|             |             |               | 5/27/93, p.1)          |
+-------------+-------------+---------------+------------------------+
| 18          | Approx. 5   | May 27th,     | \"Reconnected Again;   |
|             | mi SE of    | 1993          | The Pass               |
|             | Aspen,      |               | \[Independence Pass\]  |
|             | Colorado;   |               | Opens Early\--A        |
|             | T. 11 S.,   |               | mudslide Thursday      |
|             | R. 84 W. NE |               | morning \[May 27th\]   |
|             | 1/4 of NW   |               | about three-quarters   |
|             | 1/4 of      |               | of a mile from the     |
|             | sect. 2/    |               | gate threatened the    |
|             |             |               | opening of the pass.   |
|             | 9600 ft.    |               | But highway crews      |
|             |             |               | dispatched several     |
|             |             |               | loaders to the slide   |
|             |             |               | and were able to clear |
|             |             |               | the debris.\" (Aspen   |
|             |             |               | Daily News, 5/28/93,   |
|             |             |               | p. 1 and 6)            |
+-------------+-------------+---------------+------------------------+
| 19          | Approx. 5   | May 8th, 1996 | \"The flow \[debris    |
|             | mi. NW of   |               | flow\] occurred on May |
|             | Si          |               | 8th just after noon.   |
|             | lverthorne, |               | The flow was about 6   |
|             | Colorado;   |               | ft deep and the        |
|             | T. 4 S., R. |               | highway \[Colorado     |
|             | 78 W., NE   |               | Highway 9\] was        |
|             | 1/4 of NW   |               | blocked for a couple   |
|             | 1/4 of      |               | of hours.\" (Wes       |
|             | Sect. 15/   |               | Gauff, Colorado        |
|             |             |               | Department of          |
|             | 8700 ft.    |               | Transportation,        |
|             |             |               | personal commun.,      |
|             |             |               | 1996)                  |
|             |             |               |                        |
|             |             |               | The debris flow        |
|             |             |               | location is            |
|             |             |               | approximately 6 miles  |
|             |             |               | northwest of the       |
|             |             |               |                        |
|             |             |               | I-70 Silverthorne      |
|             |             |               | exit. The failure      |
|             |             |               | began as a slump on    |
|             |             |               | the hillside           |
|             |             |               | approximately 100 ft   |
|             |             |               | above and 300 ft west  |
|             |             |               | of the highway. The    |
|             |             |               | movement transformed   |
|             |             |               | into a debris flow     |
|             |             |               | that travelled         |
|             |             |               | approximately 400 ft   |
|             |             |               | down the hillside and  |
|             |             |               | across and beyond      |
|             |             |               | Highway 9.             |
+-------------+-------------+---------------+------------------------+
| **          | **          | **DATE OF     | **DESCRIPTION/SOURCE   |
| LANDSLIDE** | LOCATION/** | OCCURRENCE**  | OF INFORMATION1**      |
|             |             |               |                        |
| **EVENT     | **          |               |                        |
| NO.**       | ELEVATION** |               |                        |
+-------------+-------------+---------------+------------------------+
| 20          | Approx. 1   | May 13th,     | \"I first observed     |
|             | mi. SW of   | 1996          | cracks opening in the  |
|             | Aspen,      |               | snow covering the      |
|             | Colorado;   |               | slide on Sunday May    |
|             | Keno Gulch  |               | 5th. There was 3 to 5  |
|             | in the      |               | ft of snow on the      |
|             | Castle      |               | slide at that time\"   |
|             | Creek       |               | (Jim Blanning,         |
|             | drainage/   |               | personal commun.,      |
|             |             |               | 1996).                 |
|             | 9600 ft.    |               |                        |
|             |             |               | \"The first debris     |
|             |             |               | flow came down the     |
|             |             |               | mountain \[Keno        |
|             |             |               | Gulch\] on Monday, May |
|             |             |               | 13th at about 4:30 pm. |
|             |             |               | A second came down the |
|             |             |               | next day \[Tuesday,    |
|             |             |               | May 14\] at about 4:00 |
|             |             |               | pm. The parking lot    |
|             |             |               | was covered with mud   |
|             |             |               | and debris about 5-ft  |
|             |             |               | thick, six cars were   |
|             |             |               | virtually buried (4    |
|             |             |               | were totalled). The    |
|             |             |               | mud and debris flowed  |
|             |             |               | into and structurally  |
|             |             |               | damaged the Music Hall |
|             |             |               | and partially filled   |
|             |             |               | the large pond beside  |
|             |             |               | the Music Hall.        |
|             |             |               | Neither flow was       |
|             |             |               | moving so fast that    |
|             |             |               | you couldn\'t walk     |
|             |             |               | away from it.\" (David |
|             |             |               | Pearcy, Director,      |
|             |             |               | Aspen Day School,      |
|             |             |               | personal commun.,      |
|             |             |               | 1996)                  |
+-------------+-------------+---------------+------------------------+

1Information in brackets has been added by the author for the purpose of
clarification.