Table 2. Key for Identification of Common Sandstones, Pebbly Sandstones and
Conglomerates.
Step 1.0 Examine the side of the core to determine whether the rock is made up mostly
of sand grains or contains pebble size pieces of rock or streaks of coal as well as sand.
1.1 If there areno or very few pebbles or coal streaks (e.g. 18L and 18R), proceed to step 2.0.
1.2 If there areconspicuous or numerous pebbles or coal streaks (e.g. 39L and 41R )proceed to step 6.0.
Step 2.0 Examine the side of the core to determine its color and test its resistance to
impact. If
the core is very hard and dark gray or tan, apply a small drop of 10% hydrochloric acid.
2.1 If the core isgray, fractures with relative ease and in some cases has abundant mica flakes on broken
butt ends
(e.g. 18L, 29L, 32R, 36L, 38L, and lower 28L), and does not effervesce when
10% hydrochloric acid is applied, the rock belongs to the Gray Sandstone group or 540.
Proceed to
step 3.0.
2.2 If it iswhite or very light gray, often hard and brittle upon impact, with a sparkling or sugary
appearance
(e.g. 23L, 30L, 34R, and upper 28L) and does not effervesce when 10% hydrochloric
acid is applied,
the rock belongs to the Crystallized Sandstone group or 550. Proceed to step 4.0.
2.3 If it isgray to light gray and somewhat grainy but very hard, dense and tough upon impact (e.g.
24L, 30R,
35R and upper 28R), and does not effervesce when 10% hydrochloric acid is applied, the
rock
belongs to the Hard Sandstone group or 560. Proceed to step 5.0.
2.4 If it is gray and grainy, hard, dense and tough upon impact (e.g. 26L and 26R) and effervesces
when 10% hydrochloric acid is applied, the rock is a Gray Carbonate Cemented
Sandstone, Calcite or 640 CaC03.
2.5 If it isgray and grainy, hard, dense and tough upon impact, and the broken butt end is deep
brown with a
sugary texture (e.g. 27L, 27R and lower 28R), and does not effervesce freely when 10%
hydrochloric
acid is applied, the rock is a Gray Carbonate Cemented Sandstone, Silderite or 640
FeCO3.
Step 3.0 Examine the side of the core to determine the presence of streaks, lines or spots.
If they
are present, note their orientation and thickness.
3.1 If the core hasno streaks, lines or spots (e.g. 18L and18R), the rock is a Gray Massive Sandstone or
544.
3.2 If it hasthin streaks or lines that are inclined to the sides of the core (e.g. 29L and 29R), the rock
is a Gray Crossbedded Sandstone or 541.
3.3 If it hasthin wavy streaks oriented at right angles, or nearly so, to the sides of the core (e.g. 31L
and 31R), the rock is a Gray Sandstone with Shale Streaks, Rippled or 543 RIP.
3.4 If it hasthin flat streaks that are oriented at right angles to the sides of the core (e.g. 33L and
33R), the rock is a Gray Sandstone with Shale Streaks, Flat or 543 FLT.
3.5 If it hasan irregular spotty or mottled appearance with light and dark gray streaks or spots with
irregular orientation (e.g. 36L and 38L), proceed below:
If the spots or tubesare surrounded by carbonaceous (coaly) films as on page 36 or there are numerous
carbonaceous streaks (e.g. 37L and 37R), the rock is a Gray Rooted Sandstone or 547.
If they lack carbonaceous films and the rock has a "lumpy" appearance (e.g. 38L and 38R), the
rock is a Gray Burrowed Sandstone or 548.*
If they do not clearly show features illustrated on 36L, 36R, 37L, 37R, 38L and 38R and
described above, the rock is a Gray Churned Sandstone or 546.*
Step 4.0 Examine the side of the core to determine the presence or absence of streaks,
lines or
spots. If they are present, note their orientation and thickness.
4.1 If the core has-
no streaks or lines (e.g. 22L, 22R, 23L and 23R), the rock is a Crystallized Massive
Sandstone or 554.
4.2 If it has thin streaks or lines that are inclined to the sides of the core (e.g. 30L), the rock is a
Crystallized Crossbedded Sandstone or 551.
4.3 If it hasthin wavy streaks oriented at right angles, or nearly so, to the sides of the core (e.g. 34L
and 34R), the rock is a Crystallized Sandstone with Shale Streaks, Rippled or 553
RIP.
4.4 If it has an irregular spotty appearance with light and dark streaks or spots with irregular
orientation, the rock is a Crystallized Churned Sandstone or 556.*
Step 5.0 Examine the side of the core to determine the presence or absence of streaks or
lines. If
they are present, note their orientation and thickness.
5.1 If the core hasno streaks or lines (e.g. 24L, 24R, 25L and 25R), the rock is a Hard Massive Sandstone
or 564.
5.2 If it has thin streaks or lines that are inclined to the sides of the core (e.g. 30R), the rock is a Hard
Crossbedded Sandstone or 561.
5.3 If it has thin wavy streaks oriented at right angles, or nearly so, to the sides of the core (e.g. 35L
and 35R), the rock is a Hard Sandstone with Shale Streaks, Rippled or 563 RIP.
5.4 If it hasa spotty appearance with light and dark streaks or spots with irregular orientation, the
rock is a Hard Churned Sandstone or 566.*
Step 6.0 Examine the core to determine the character of the sandy material between the
pebbles.
6.1 If the sandy material isgray, grainy and relatively soft (e.g. 39L, 39R, 41L and 41R), proceed to step 7.0.
6.2 If it is white or very light gray and very hard and brittle (e.g. 43L and 43R), proceed to step 8.0.
6.3 If it is gray to light gray and somewhat grainy but hard and tough upon impact (e.g. 44L and
44R), proceed to step 9.0.
Step 7.0 Examine the sides of the core to determine the character of the pebbles.
7.1 If the pebbles arelarge irregularly shaped spars of bright coal (e.g. 39L), the rock is a Gray Sandstone
with Coal Spars or 749.
7.2 If they arethin flattened pieces of coal, grouped into well defined layers (e.g. 39R), the rock is a
Gray Sandstone with Coal Bands or 748.
7.3 If they arepieces of shale or sandy shale (e.g. 40L), (may also contain some quartz pebbles and
coal), the rock is a Gray Shale Pebble Conglomerate or 742.
7.4 If they areround or oblong bodies which are orange or brown (e.g. 40R), (may also contain some
quartz pebbles and coal), the rock is a Gray Ironstone Pebble Conglomerate or 743.
7.5 If they arepieces of shale and ironstone (e.g. 41L), (may also contain some quartz pebbles and coal),
the rock is a Gray Shale and Ironstone Pebble Conglomerate or 741. (This term can
also be used when shale and ironstone cannot be differentiated.)
7.6 If they arerounded, dark, spotted or streaked pebbles (e.g. 41R, 42L and 42R), (may also contain
some quartz pebbles), the rock is a Gray Rock Pebble Conglomerate or 745.
Step 8.0 Examine the sides of the core to determine the character of the pebbles.
8.1 If the pebbles arehard, white or gray quartz pebbles (e.g. 43L and 43R), the rock is a Crystallized Quartz
Pebble Conglomerate or 754.
Step 9.0 Examine the sides of the core to determine the character of the pebbles.
9.1 If the pebbles arepieces of shale or sandy shale (e.g. 44L), (may also contain some quartz pebbles and
coal), the rock is a Hard Shale Pebble Conglomerate or 762.
9.2 If they areround or oblong bodies which are brown or orange (e.g. 44R), (may also contain some
quartz pebbles or coal), the rock is a Hard Ironstone Pebble Conglomerate or 763.
*These rocks in some cases contain fossil shells. Please see page 79.