Landforms at the angle of repose

Colluvium is material moved by gravity. Mass wasting is a generic term for all manner of gravity-driven processes and deposits. Colluvial or talus fans have much in common with alluvial fans, and may grade imperceptibly into them. Colluvium rests at the angle of repose; it’s steeper than alluvial fans and material is more angular than water-transported rock.

Here are two kinds of habitats on colluvial slopes, keyed to frequency of disturbance.

Two kinds of habitats on colluvial slopes, keyed to frequency of disturbance.

Size of colluvial deposits depends upon the jointing pattern of source rock in cliffs above, intensity of freeze-thaw action, and, of course, time. Southeast colluvium has been accumulating for about 12,000 years, an eyeblink compared to the life span of talus cones in unglaciated mountains of the desert southwest, for example.

In this section

Escape to ‘beautiful face’

Outdoors with teachers Yadaa.at Kalé means beautifully adorned face, of slopes rising northeast from the highschool named for them (JDH).…

Mass wasting finale

In class—our penultimate Wednesday—we reviewed Bay&Valley day, and then transitioned to the concluding Saturday field trip focusing on ‘serious-stuff-coming-downhill.’ For…

2022 | Richard Carstensen | Landforms class archives

Rockslide snagswamp

Unraveling the origins of a fascinating pond Til’héeni, dog salmon stream (Salmon Creek) is a new addition to featured Áak’w…

2019 | Richard Carstensen | 4-minute slideshow

Spring avalanches

Snowslides and critters Last year around this time I posted video and thoughts about the relationship of critters to avalanches—both…

Downhill disturbance

Avalanche and wildlife It’s hard to think long about mountain goats—especially here on the precipitous coast—without wondering how they deal…

2022 | Richard Carstensen | 3 minute slideshow

2022 avalanches

Snowslide cartography When weather clears and risk-level drops, I’ve been trying to keep up with this winter’s avalanches by flying…

Avalanche mapping

Releases in Nettleslide (Behrends path) & Last Chance Goatwatching in winter leads inevitably to fascination with avalanches. Yesterday, Feb 12,…

2022 | Richard Carstensen |

Roads of ‘Northeast Chich’

Slideshows: Xunaa Káawu Each summer, I try to get over to Hoonah to help my wife Cathy with her research…

2021: 2019 | Richard Carstensen | Slideshows, 8- & 4 minutes

Teachers’ outings, 2021

Year-3: Estuaries & steep places Two kinds of landforms & habitats have consumed my attention this winter and spring—estuaries and…

2021 | Richard Carstensen | 60 page journal & course manual

108 days on mountain goat winter range

Motion-detector camera at 1,200 feet On December 12th, 2020, Steve Merli and I placed a game-cam in mountain goat winter…

2021 | Richard Carstensen | 12-minute slideshow

Dzisk’w liu kaadi: little owl snowslide

Avalanches in Goatlandia Yesterday (20210304), avalanches were triggered above the Thane Road runout on Snowslide Creek. Several folks posted impressive…

2021 | Richard Carstensen | 80-second slideshow

New years Jánwu party at Centergrove

More the merrier Our coastal goats—since October anyway—have been hanging out in pretty small, compatible groups, dispersed all over Goatlandia…

2021 | Richard Carstensen | 4 minute slideshow

Nature near the schools: Landforms

Powerpoint & script for Discovery Nature Studies I didn’t come to geology by natural inclination. I was gently nudged by…

1990 | Richard Carstensen | powerpoint & script

Special trees in Nettle Slide

New angles on Tʼóokʼ dleit ḵaadí, nettle snowslide (Behrends Slide) Late September, 2020  It’s probably time we stopped calling this…

2020 | Richard Carstensen | 90 second slideshow

Blackwell City Walk: info packet

Another great idea from Mike Cathy Connor and I (Richard Carstensen) have inherited a tradition spearheaded by our friend Mike…

2019 | Mike Blackwell, Richard Carstensen & Cathy Connor | 27 pages

Mid-May on Shaa Tlaax

Goats, geology & zonation on Shaa Tlaax, moldy top (Mt Juneau) Video-journal of the flora, fauna, and geomorphology that hikers…

2019 | Richard Carstensen | 4 minutes

Kaxdigoowu Héen (Montana Creek): presentation for SEAL Trust

Slideshow in two parts Kaxdigoowu Héen, going back clearwater has been one of my favorite places since I first explored…

2019 | Richard Carstensen & John Hudson | slide show in 2 parts: 38 & 22 minutes

Staff hike in Dzantik’i Héeni basin

On a sleety December 11th, 2018, Discovery Southeast staff (and Clay Good, board) hiked together in the lower valley of…

2018 | Richard Carstensen | 7 minutes

Behrends avalanche

Three days after an avalanche came down Behrends Slide, near Juneau, Alaska, I went up for some raven’s-eye perspectives. The…

2017 | Richard Carstensen | 2.5 minutes

Repeat photography summary report

Documenting change through repeat photography in Southeast Alaska Carefully framed retakes of historical photographs documenting vegetation and landform change in…

2005: 2nd ed, 2013 | Richard Carstensen, Kathy Hocker | 39 pages