Jd _wm _wm _wb _wm _wb _wb Zcm _wb _wm _wm Zcm _wb Zcm _Zl _wb _wmq _Zlp _Zlp ¬ « 7 ¬ « 9 ¬ « 8 ¬ « 6 ¬ « 5 ¬ « 4 ¬ « 3 ¬ « 1 ¬ « 18 ¬ « 17 ¬ « 16 ¬ « 15 ¬ « 14 ¬ « 13 ¬ « 12 ¬ « 11 ¬ « 10 ¬ « 2 1500 1400 1300 1200 1600 1100 1000 900 1700 1300 900 1600 1300 1100 1500 1500 1300 1300 1600 1100 1200 1500 1400 1300 1200 1600 1400 1100 1400 1300 1600 1200 1400 1600 1000 £ ¤ 40 Gambrill Park Road § ¨ ¦ 70 $ Catoctin Trail (blue) Yellow Poplar Trail Black Locust Trail Green Ash Trail Red Maple Trail White Oak Trail Trails GAMBRILL STATE PARK MAP OF GEOLOGIC FEATURES High Knob Contour interval 20 ft 0 1 0.25 0.5 0.75 Miles Ridge Road GEOLOGIC UNITS Diabase dike(s) dark gray to black diabase; weathers to red-brown boulders Jd Catoctin Formation Zcm greenish metamorphosed basalt Loudoun Formation _Zl dark gray conglomerates and phyllites; contains white quartz veins dark gray phyllite (subunit) _Zlp Weverton Formation mainly gray, metamorphosed sandstones (quartzites), conglomerates and metamorphosed shales (phyllites) Maryland Heights Member _wm interbedded sandstones/quartzites, shales and conglomerates light gray quartzite (subunit) _wmq _wb sandstones/quartzites Buzzard Knob Member Document available online from the MARYLAND GEOLOGICAL SURVEY www.mgs.md.gov