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Table 2 |
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VML-based mapping units
and morphostratigraphic characteristics of alluvial fan deposits in Death
Valley and their |
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comparison with other
previously used mapping units in the study region |
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Mapping |
Oldest LU |
VML-based |
Referred general |
Characteristics of alluvial fan |
Bull (1991) |
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Dorn (1988) |
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unit |
observed |
age (ka) |
climatic condition |
morphostratigraphy |
Fan unit |
(ka) |
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Fan unit |
(ka) |
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Qu1 |
LU-1 |
0 - 12 |
drier/arid |
Active channel deposits; or deposits in recently |
Q3 - Q4 |
0 - 12 |
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Q3b |
0 - 9.5 |
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abandoned channels
and at fantoe |
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Qu2 |
LU-2 |
12 - 18a |
wetter/semiarid |
Bar-and-swale
topography; occasionally with |
Q2c |
12 - 70 |
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Q3a |
14 - 50 |
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incipient development
of desert pavement |
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Qu3 |
LU-3 |
18 - 24 |
transitional |
Reworked fan surfaces of Qu4 or older; |
Q2c |
12 - 70 |
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Q3a |
14 - 50 |
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little development of
desert pavement |
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Qu4 |
LU-4 |
24 - 74 |
wetter/semiarid |
Best-developed pavement with incipient |
Q2c |
12 - 70 |
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Q3a |
14 - 50 |
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drainage systems; no
petrocalcic horizon |
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Qu5 |
LU-5 |
74 - 128 |
drier/arid |
Smooth well-developed pavement with a |
Q2b |
70 - 200 |
Q2b |
105 - 130 |
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petrocalcic horizon |
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Qu6 |
LU-6 |
128 - 190 |
wetter/semiarid |
Dissected smooth pavement; well-developed |
Q2b |
70 - 200 |
Q2a |
140 - 170 |
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petrocalcic horizon;
often inset within Qu7 |
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Qu7 |
LU-7 |
190 - 245 |
drier/arid |
Dissected pavement; well-developed petrocalcic |
Q2b |
70 - 200 |
Q1b |
490 - 600 |
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horizon; often inset
into Qu8 |
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Qu8 |
LU-8 |
245 - 303 |
wetter/semiarid |
Ridge-and-ravine (ballena) topography; petro- |
Q2a |
400 - 730 |
Q1a |
650 - 800 |
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calcic rubble easily
visible on fan surfaces |
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Qu8+ |
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> 303 |
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Ridge-and-ravine topography; remains of oldest |
Q2a |
400 - 730 |
Q1a |
650 - 800 |
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fan deposits perched
on bedrock at fanhead |
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a The lower boundary of varnish layering unit LU-2 is likely
around 18 ka (Liu, unpublished data). |
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