Surficial geology Archives

‘Flesh’ atop of the ‘bones’ of bedrock geology

The Surficial geology section is divided into Alluvial landforms & processes, Glacial history & landforms, Glacial rebound & coastal landforms, and Mass wasting. Explore those sub-categories or find general information below. You can also view the entire JuneauNature hierarchy at this site map.

Surficial geology is the study of loose, unconsolidated material overlying the bedrock foundation. These layers were deposited, rearranged and eroded by glaciers, fluctuating sea level, streams, landslides, and bulldozers. While bedrock geologists tend to think in time-frames of millions of years, the surficial story is usually faster paced, taking place over millennia and mere centuries.

Surficial versus bedrock geology. For more comprehensive discussion, see Reading Southeast Alaska’s landscape.

While bedrock geologists tend to think in time-frames of millions of years, the surficial story is usually faster paced, taking place over millennia and mere centuries. On the surficial geology map, I’ve divided landforms into 5 age groups. In the pop-ups, these are listed in the ‘geol_age’ field:

triassic: applied only to a couple bare-bedrock roches moutonees near Mendenhall Glacier
early holocene: marine, glacial and alluvial formations dating back to shortly after the great ice age, ~10,000 years ago
neoglacial: dating to just the last few millennia
little ice age: mostly formed since peak of the last glacial advance in the mid-1700s
anthropocene: built or excavated features mostly since 1950.