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California Mountain Atlas


Contra Costa County

PLEASE NOTE:  This is an experimental page that demonstrates the different kind of "orometric data" that can be gathered for a mountain summit.  Feedback is welcome.

The Mountain
Orometric (most recent) Height  --  NEW HEIGHT -- 
3,864 [i]
Clean Prominence 3,109+20 [ii]
Prominence Rank 42nd in State
37° 53' N
121° 55' W approximate

Summit Elevation Information
NAVD88 Elevation (benchmark)
3,864' [iii]
USGS Published Elevation (NGVD29):  --  OLD HEIGHT -- 
3,849' [v]
Summit Interval (Summit Error Range): 0 [vi]
Benchmark Name (if any): Mount Diablo
Benchmark PID: HS5120
Known elev. difference BM to summit: 0' [iv]
GEOID99 Height -31.73m  

Prominence Information
Referenced Elevation + Summit Error 3849'
Elevation of Key Saddle (NGVD29) 740
Key Saddle Interval (error range) 20
Key Saddle Location 37º 46' 42"N, 121º 39' 42"W
Key Saddle Description 1 mi. NNW of Altamont Pass

Lineage Information
NHN (500' rule) Eylar Mtn. (Copernicus Cell)
NHN (2000' rule) Copernicus Peak
PP (Prominence Parent) San Benito Mtn.
IP (Island Parent) Mt. McKinley
Lineage Group (Level 2 - Ultras) Pinos sub Whitney
Diablo: San Benito: Pinos: Whitney

Other Mountain Metrics
Insularity (Dominance) 80.7%
Isolation (distance to higher ground) 34.3 mi.
courtesy Greg Slayden
Isolation (Location) Eylar Mtn. (SE) unverified
Total View Area
coming soon

Access Information
Ownership California State Park vii
Access Public, from within park
Information not guaranteed
Paved Road to Top

Shortest distance and Gain to Summit (RT)
100 ft.
Class (YDS) 1
Notes Original summit is preserved inside museum.  Miles of trails on mountain.

General Information:

Mount Diablo is the highest point in Contra Costa County.  Widely visible from all over the Bay Area and the Central Valley, the summit is rumored (incorrectly) to have the greatest viewshed in the country and second greatest in the world.  Mount Diablo is the base meridian for most of Central and Northern California and Nevada.   


California State Park website

Maps of all P500 summits on the cell:      Diablo Cell Map

List of all P500 summits on the cell:

reformatted: January 5, 2005
Rank Summit Elevation E(e) Prominence Saddle S(e) Lat. Long.

1 Mt. Diablo 3849
3109 740 20 37º52'52"N 121º54'51"W
HP Sunol Ridge 2191
1721 470 10 37º37'12"N 121º55'21"W
Vollmer Peak 1905
1305 600 20 37º53'00"N 122º13'19"W
Rocky Ridge (mult.) 2024 16 1244 780 20 37º48'54"N 122º03'40"W
5 BM 2581 2581
1061 1520 40 37º48'52"N 121º48'30"W
6 Wiedemann Hill 1851
1051 800 20 37º44'18"N 121º59'41"W
7 Pt. 1894 1894
928 966
37º56'35"N 121º53'27"W
8 BM Hills 1483
823 660 20 37º56'13"N 122º07'41"W
9 Brushy Peak 1702
742 960 20 37º46'03"N 121º42'10"W
10 HP Walpert Ridge 1852
635 1217
37º37'34"N 121º57'41"W
11 Black Point 1791
619 1172
37º54'41"N 121º57'35"W
12 North Peak 3557
597 2960 40 37º53'35"N 121º54'01"W
13 Pt. 1272 1272
592 680 40 37º50'26"N 121º44'36"W
14 BM Abrott 1012
572 440 20 37º57'14"N 122º14'56"W
15 Pt. 1160+ 1160 40 560 600 40 37º48'29"N 122º07'33"W
16 BM Chabot 2 808
508 300 20 37º43'27"N 122º07'09"W
17 Oyster Point 2106
506 1600 40 37º49'49"N 121º52'40"W
18 Eagle Peak 2369
489 1880 40 37º54'07"N 121º56'19"W

[i]     Orometric height is the author's best estimate of the true elevation of the mountain based on the NAVD88 datum of the benchmark (if any) plus any known elevation difference between the benchmark and the highest natural point on summit.

[ii]    Clean prominence is based on the USGS published map elevations of the summit and saddle (NGVD29 datum).

[iii]   This is the recently adjusted official height of the benchmark, which may not yet be reflected on USGS maps.

[iv]    In many cases the benchmark is not on the true summit, and the following elevation could be added to the "official" elevation to get the true natural height of the mountain.  (NGS) means that the difference is described by the NGS on the benchmark datasheet.  (FIELD) means that a hiker has observed this difference in the field.

[v]     Elevation on 7.5' topographic map, used in computation of prominence.  Widely regarded as official elevation.

[vi]    If no spot elevation is given on map, then the lower contour is used as the summit height and the contour interval indicates the possible range of true values.

[vii]   Hikers are advised to confirm access information before attempting an approach.  We can not take any responsibility for inaccurate information on this website.,