1

1

1

1

1

1

1

1

11

1⁄2

11

1

1

1

1

11

111

1

11 11111

1

1

1

1 1

1

11⁄2

11

1

1

1

1⁄2

1⁄2

1

1⁄2

1

1

1

11

1

1

1

1⁄2

1

11

1

1

1

1

1

1 1

1

1

11

1

1

11

1

1

1⁄21

111

1

1

1

1

1 1

11

1

1

1

1

1

1

1

1⁄2

1

1

1⁄2

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1⁄2

1

1

1

1

1

11

1

1

1

1

1

1

1

1

1

11

1

1 1

1

111

1

1

11

1

1

1

1

1

1

1

1 11

1

1W S

1

1

1

1

1

1

11

1 1

1

1

1

11

1

1 1 1

1 11

11

1

1

1

1

1

1

11

1

1

1

1

1

1

1

11

1

1

1

1

1

1

1⁄2

1

1

1

1

1

1

1

1

1

11

1

1

1

1

1

1⁄2

1

1

1

1

1

1

1

1

11

1

1

1 1

1

1

1

1

1

11

1

1

1l

1

1

1

1

11 1 1

11

1

1

1

1⁄2

11

1

1

1

1

1

1

11⁄2

1

1

1

1

1

1 1

1

1

1

1

1

1 1

1

1

1

1

1

1

1

111

1

1 1

1

11

1

1

1

1

1

1

1

1

1

11

1

1

1

1 1

1

1

1

1

1

1

1 1

1

1 1

1

1

1

1

1 1 11

1

1

1

1

1

1

11

1

1

1

1

1

1

11 1⁄2

1

1

1

1 1

1

1

1

1

1

1⁄2 1 1

1

1

1

1

1111

1

111⁄21

11 1 1

1 1

11

11

1

1

1⁄2

1

1

1

1

1 1 1

1

1

1

1

1 11

1⁄2

1

1 1

1

1⁄2

1

1

11 æ1S

1

1

1

1

1

1 1 11

1 1

11

1

11

1 1

1

1

1

1

1

1

1

1

1

11

1

1

1

1

1

1 1 1

1

1

1

111

11

1

1

1

1

11

1

1

11

1 11

1

1 11⁄21 1

1

1

1

W S

1

1 1

1

1

1

1 W

1S

£87

1£j

äl

1

1

1

1

1

æ

S

1

1 1

1

1

1⁄2

1 1

1

1

1

1⁄2

1

1

11

1

1

1

1 1

1

1⁄2

11⁄21

1

1 1

1⁄21⁄2

11

1

11⁄2

1

11

1

1

11

11

1

111

1111

1

1

1

1

1

1 1⁄2 1 1

11 11⁄2

1

1 11

1 11 1

1

1

1 1 1 1

1

1

1

1

1

1

1 W S

1

8£7

1

1

1

1

1⁄2

1

1

11

1

1

1

1

11

1

11

1

1

1

111

1⁄2

1

1

1

1

1

1 1

1

1

111

1

1

1

1 1

11

1

11

1

1

1

1

1

1

1

1 1

1

1⁄2

1

1

1

1

1

1

1⁄2

1⁄2

1

1

1

1 11

1

1

1

1

11

1

1

1

1 1⁄2

1

1

1

1

1

1

1

1

1

11⁄2

1

1

11

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1⁄2 1

1

11

1

1 1

1⁄2

11⁄2

1

1

1

1

1

1

1

1 1

1

1

1

1

1

1⁄2

1

1

1

1

1

1

1

1

1

1

1

1⁄2

1

1⁄2

1 1

1

1

1

1

1

11

111

11

1

1⁄2

1

1

1

1

1

1

1

1

1⁄2

1

1

11

1

1

1

1

1

1

1

1

1 1

1l

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

11

1

11

11 1

1

1

1

11

11

1

l 1

1

111⁄21

1

11

1

1

11⁄2

1

1 æ S

8£7

W

1ä

S

£87

1

1

1⁄2

11

1

1

1

1

11

1

11

11

11

1

1

1

1

1

1

1

1

1

1⁄2

1

11

1

1

1

1⁄2

1

1

1⁄2

Sæ 1⁄2

1

l

1 1

1

1

1

1⁄2

1

1

1

1

1

1

1

1

11

1 11 1

1

11

1 11

11

1

11⁄21

111 1

11

1

1

11

1

1 1

1

1

11

1

1

1

11⁄2

1

1

1

1

1

1

1

111

1

1

1

1

1

1 1

l

1

1

j

£

s

£j1

l

1l

' 1

£j

ä

£j

>

?

?

>

>

?

?

? ?

?

?

?

?

?

?

?

?

?

? ?

?

?

?

?

?

?

?

? ?

?

?

?

?

?

,

,

,

,

,

,

E

E

E

E

E

Jm

Jhc

Jcr

Qya

Jm

Kgm

Kgm

Qoa1

Jhc

Jm

Jm

Kc

Qoa

Jhc

Kgm

Jcr

Qoa

Qls

Jhc

Kgm

Kc

Qls

Jm

Qya

Jcr

Jcr

Qoa2

Qya

Jm

Jm

Jhc

Jhc

Jhc

Qya

Jcr

Jhc

Qya

Jcr Jm

Jcr

Kgm

Jm

Qoa2

Jcr

Kgm

Qya

Jcr

Kgm

Jhc

Kc

Jcr

Jcr

Kgm

Jcr

Jcr

Jcr

Jm

Jm

Jm

Jm

Jm

Qc

Jhc

Jm

Qya

Jhc

Jhc

Qoa

Jcr

Jm

Jm

KJem

Jhc

Jhc

Kgm

Qya

Qya

Qya

Jm

Kc

Jcr

Jm

Qoa

Jm

Jm

Jm

Jhc

Qya

Jhc

Qya

Qya

Kgm

Qc

Jm

Jcr

Jm

Qya

Kgm

Jcr

Qc

Qls

Qc

Qoa

Qya

Qya

Qya

Qya

Jhc

Jm

Jm

Kc

Qoa

Jm

Qya

Jm

Kgm

Qya

Kc

Jcr

Jcr

Kgm

Jm

Kgm

Kl

Qya

Jm

Jm

Qya

Jhc

Qya

Jcr

Qoa3

Jhc

Jm

Jm

Qoa4

Qya

Qya

Kl

Qya

Jm

Qoa

Kl

Qc

Qya

Qoa

Jcr

Qya

Kc

Qc

KJem

Jm

Jhc

Jhc

Qoa

KJem

Jcr

Jm

Jm

Qoa

Qc

Kl

Jm

Qoa

Jm

Qya

Kgm

Qc

Kl

Jcr

Jm

Kl

Kl

Qc

Jm

Jm

Kl

Jhc

Jm

Qoa

Kl

Jcr

Kl

Kl

Qya

Qya

Qc

Jm

Qya

Qoa2

Qya

Jm

Qoa1

Qc

Jm

Jm

Jm

Jm

Qya

Jm

Jm

Kc

Kl

Qya

Kgm

Jm

Kgm

Qya

Jhc

Kgm

Jm

Jm

Jm

Kl

Jm

Jm

Qoa4

Jcr

Jm

Jm

Kgm

Jm

Kgm

Jhc

Jm

Jm

Jcr

Kl

Kgm

Kc Kl

Kgm

Jhc

Qoa1

Qoa

Jcr

Qya

Qya

Kgm

Jm

Jm

Jhc

Kc

Jm

Kl

Kgm

Qc

Kl

Jhc

Jm

Kgm

Jm

Qya

Jm

Jhc

Kgm

Kgm

Kl

Jm

Jm Kgm

Jm

Jcr

Kgm

Jcr

Jm

Kgm

Kc

Qya

Jm

Qya

Jhc

Jhc

Jm

Jm

Kgm

Kgm

Jm

Kgm

Jhc

Jhc

Jcr

Jcr

Jm

Jm

Jhc

Kl

Kgm

Kgm

Kgm

Kgm

Kgm

Jcr

Kc

Kc

Kc

Kc

Qoa

Qya

Jm

Kgm

Kc

Kc

Jcr

87 64

84

68 80 78

65

78

83

88

84 80

88

88

86

77

79

72

86 80

81

87 75 66

55

52

71 71

85

82

83

85

88 82

86

79

72

88

87

65

87

54 70

69

60

63 63

66

71

50 69

75

80

70

74 88

65

82

77

72

73

84

83

86

72

72

82 84

87

77

73

71

67

84 84

70

84

72

61

77

62

40

64

88 72

65

76

82

87

71 62

83

77

88

85

79

53 78

78

55

52

71

76

72

63

73

72 66 63

76

84

80

75

82

84

85

86

80

62

60

76

80 66

84

87

83

82

81

46

86 86

63

83

78

74

81 70

86 65

61

82

80

78

70

65

80

44

30

81

86

88

69

79

56 88

80

79

69

88

88

81

69 85

83

77

73

88

72

83

82

85

89

84

86 89

80

49

34

78

72

43

85

86

68

70

80

64 71

80

84

85

61

69

75

67

71

87

85

70

77

85

89

73

86

88

89

89

78

73

84

84

63

80

57

75

73 71 83

89

88

84

72

72

78

71

79 82

83

78

85 82

85

87

85

83

86

68

85

85

87

87

82

87

64

89

85 83

89

73

85

75

72

82

79 83

85

74

77

70

66

65

82

83 87

83

85

84

85 82

88 77

86

78 50

82

88

81

78

68

73

85

84 88

70 69

85

84

62

83

75

77 72

70 70

78

85

67 75

65 74

65

64 88

86 75

84

84

78

55

72 77

75

85

83

75 73

76

83

89

86

81

82

87

87

76

81

81

89

60

71

68

73

80

77

77 84

75 72

73 84 61

82

78

72

70 78

58

85

86 59

57 89

65

85

84

76 73

77

88

77

82 87

87

76 82 88 63

72

75

84

81

74 72

81

67

70 86

61

79

79 72

80

63

79

83

86

80 73 79

89

67

82

60

69

70

60

86

79

85

89

87

79

81

83

77

82

83 87

82

82

49

78 75

74

80

78

76

77

79 88

43

63 75

59

64

64

62

57

74

73

73

76

73 86

84

89 83

51 79

81

31 85

64

87

82

74

80

71

77

85

78 84

77

52

60

79

82 68

80

77

80

83

83

73

71

86 89

87

86

79

88

80

85

79

89

87

87 86

84

89

84

85

83 83 80

81

83 85

80

71

87

87

87

85

78

74

89

88 88

86

79

68 52

85

69

83

83

79

60

81

79

53 86

78

73

68

72

77 87

70 76

67

82 74 78

83

86

82

79

54

70

69

84

84 79 71

74

78

79

78

89

84

85

83

88

74

80

85

70

79

82

82

85

85

80

89

78 87 50

42

56

84

76

79

59

83

81

88 82

85

78

74

86 82

85

84

70

75

77

52

77

87 88 88

88 84

82

85

72

80

67

80

68

74

74

81

87

84

86

78 78

78

88 89

89 83

86

81

87

88

88

83

88

80

86

83 82 76

89

74

86 85

82

81

85

86

74

87

88

88

74

82

65

88

77

84

70

84

85

63

85

82

78 53

65

84

42

85

63

41

64

68

58 76

72

80 78

77

80

82

82

83

61

71

84

80

88

62

87

82

81

85

87

82

82

86

73

81

71

62

84

81

73

47

54

88

76

87

85

82

77

83

79

81

86

86

78

83

53

82

82

68 71 45

78

85

85

83

78

75

71

83

85 83

79

83

83

89

81

74

84

86

83

71

82

88

70 77 80

79 74

80 80

60

87

77

89

72

87

84

77

20

85

85

73 79

87

80

84

88

66

81 89

89

71

82

62

69

76

73 72

78

88

73

89

86

81

74

76

69 88

77

80

77

67 57

80

80

74

78

83

84

74 87

64

67 87

68

72 68 61 86

82 87

78 83 70

78

85

84

85

75

52

75

64 82

86

75

89

84 82

85 77

76

54

76

86

75

71

88

84 85

83

78 82

85

75 80

88

72 79

85

82

85 73 75

58

50

68

71

89

72

88

75

69

89

86

74

84

80

85 87

88 84

68

82 69

89

89 86

81

80

79

81 75 72

78

87

67 89

86

54

76

86

88

84

60

85

77

60

84

88

57

85

84

89

82

81

83 87

74

73

75

68

5447

50-58

81

77

79

87

74

23-53

50

75

30-45

42

87

ELSINORE

FAULT

ZONE

ELSINORE

FAULT

ZONE

CHARIOT

CANYON

FAULT

ZONE

San

Felipe Hills

Fault

Zone

33° 07' 30"

116° 37' 30" 33° 07' 30"

116° 30' 00"

33° 00' 00"

116° 30' 00" 116° 37' 30"

33° 00' 00"

2015

Victoria R. Todd

By

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement by the U.S. Government

This map is available online only. If it is printed on an electronic plotter directly from digital files, dimensional 

calibration may vary between electronic plotters and between X and Y directions on the same plotter, and paper 

may change size due to atmospheric conditions; therefore, scale and proportions may not be true on plots of this 

map.

Digital files available at http://dx.doi.org/10.3133/ofr9416

Suggested citation: Todd, V.R., 2015, Geologic map of the Julian 7.5’ quadrangle, San Diego County, California: U.S. 

Geological Survey Open-File Report 94–16, 18 p., 1 sheet, scale 1:24,000, http://dx.doi.org/10.3133/ofr9416.

Geologic Map of the Julian 7.5’ Quadrangle, San Diego County, California

1000 0 1000 2000 3000 4000 5000 6000 7000 FEET

1 .5 0 1 KILOMETER

SCALE 1:24 000

CONTOUR INTERVAL 40 FEET

NATIONAL GEODETIC VERTICAL DATUM OF 1929

1 1/2 0 1 MILE

MAP LOCATION

California

Base from U.S. Geological Survey

Julian 7.5’ quadrangle, 1960

(photorevised 1988)

UTM zone 11, North American Datum 1983

Manuscript approved for publication 

January 3, 1994

and Jordan G. Matti 

Susan C. Hollis, Douglas M. Hirschberg, 

Digital database and cartography by 

Geologic mapping and information by 

Victoria R. Todd, 1975–1981

ISSN 2331-1258 (online)

http://dx.doi.org/10.3133/ofr9416

EXPLANATION OF MAP SYMBOLS

Strike and dip of mineral foliation in crystalline rocks

—Dashed where approximately located; teeth on upper plate

—Solid where well located, dashed where approximately located, dotted where concealed,

75 52

l ä

—Solid where well located, dashed where approximately located, queried where probable,

Contact

High-angle fault

 dotted where concealed; bar and ball on downthrown side; arrow shows direction and amount of dip

 of fault plane; diamond symbol shows direction and amount of plunge of linear features on fault plane

 or gouge zone; arrows indicate sense of lateral displacement

Low-angle fault or glide plane

'

Vertical

Inclined

79 äj

£

Strike and dip of small fault or gouge zone (≤ 25 cm thick) —Diamond symbol shows direction and

 plunge of linear features on fault plane

1⁄2

181

Vertical

Inclined

Strike and dip of overturned bedding in metasedimentary rocks s60

1

Direction and plunge of lineation within plane of foliation

77 S

50

Syncline (Isoclinal)

Anticline (Chevron) W S

£8 7

æ S

£8 7

Small fold (wavelength ≤ 1 m) showing fold profile—Vergence (double arrows indicate steeper limb),

 direction ± amount of plunge

?

>

Landslide

Incipient slump, hachure indicates direction of possible movement 

Spring or seep

—Arrows indicate direction of movement

E

queried where location is questionable

Lineament, possible fault

Kl Leucocratic dikes (Cretaceous)—Dikes consisting of pegmatite, alaskite, aplite, and leucogranite

C.I. from 17-27

and lesser granodiorite; minor quartz diorite. Medium- to coarse-grained; weak to mylonitic foliation.

Kgm Tonalite of Granite Mountain (Late Cretaceous)—biotite-hornblende tonalite; hornblende-biotite tonalite

gabbro ± opx ± cpx ± biotite. Moderately to strongly foliated

± pyroxene ± biotite. Fine- to medium-grained smaller bodies, marginal zones of large plutons: hornblende 

gabbro ± amphibole ± opx ± olivine; amphibole-olivine gabbronorite; minor hornblende diorite, leucodiorite 

Cuyamaca Gabbro (Early Cretaceous)—Interior of large plutons: hornblende-bearing troctolite; anorthositic Kc

hypersthene ± clinopyroxene

Texturally and compositionally heterogeneous. Strongly foliated to mylonitic. Some rocks contain

biotite-hornblende quartz diorite and tonalite; lesser diorite, granodiorite, quartz monzodiorite, and gabbro.

biotite-hornblende tonalite and quartz diorite; and fine-grained (quenched), locally porphyritic

KJem Quartz diorite of East Mesa (Cretaceous and Jurassic)—Fine- to medium-grained, gneissic

locally mylonitic. C.I. = 16-30

±actinolitic amphibole ± hornblende. Contains sphene, ilmenite, allanite. Fine- to medium-grained, gneissic, 

Jcr Granodiorite of Cuyamaca Reservoir (Jurassic)—Biotite- and hypersthene-biotite granodiorite and tonalite 

corderite, garnet. Fine- to coarse-grained, gneissic to mylonitic. Average C.I. is 22

quartz-rich granitoids. Contains graphite, muscovite, tourmaline, ilmenite, sillimanite (mostly fibrous habit), 

Jhc Harper Creek Gneiss (Jurassic)—Biotite granodiorite and tonalite, lesser monzogranite; mylonitic rocks are 

submarine fan complex that received intermittent basaltic flows and sills

orthoamphibolite; metamorphosed to amphibolite facies. Protoliths interpreted as turbidites deposited on 

calcsilicate-bearing feldspathic metaquartzite; and minor small-pebble metaconglomerate, metatuff, and 

Jm Julian Schist (Jurassic and Triassic)—Interlayered, intergradational semi-pelitic, pelitic, and quartzitic schists; 

Qya

Qc

Qoa

Qoa1

Qoa2

Qoa3

Qoa4

Qls

Younger alluvium (Quaternary)—Sand, silt, and gravel in modern washes

Colluvium (Quaternary)—Sand, silt, and gravel on hillslopes; grades locally to younger alluvium

modern washes.

Older alluvium, undivided (Quaternary) —Dissected sand and gravel of alluvial fans and terraces in

Older alluvium (Quaternary)—Older materials of alluvial fan on west side of San Felipe Valley 

Older alluvium (Quaternary) —Younger materials of alluvial fan on west side of San Felipe Valley

 wall of Banner Canyon

Older alluvium (Quaternary)—Coarse alluvium beneath slide or thrust of crystalline rocks in the east 

 of tonalite of Granite Mountain

Older alluvium (Quaternary)—Alluvium at southeast end of Rodriguez Canyon composed of boulders

 of movement

Landslide deposits (Quaternary)—Landslides, slumps, and debris flows; arrows indicate direction

LIST OF MAP UNITS

Jm

Jhc Jcr

KJem

Kc

Kl Kgm

Qls

Qoa Qoa1 Qoa3 4

Qoa2

Qoa

Qc

Qya

QUATERNARY CENOZOIC

CRETACEOUS

JURASSIC

TRIASSIC

MESOZOIC

CORRELATION OF MAP UNITS

U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 94-16

APPROXIMATE MEAN

DECLINATION, 2015