Geologic File Example: Sedimentary Layers and Lenses

Geologic File Example: Sedimentary Layers & Lenses

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Both example files below represent valid forms for the geology file associated with the above figure. For file 1, line 2 of the file is “1”, therefore all surface elevations are entered as actual elevations relative to a fixed reference such as sea level (not depths) and the relationship between x, y, and elevation must be a right handed coordinate system. Note that X and Y corresponding to Eastings and Northings are used. Be careful not to reverse these.

Two special flags are used to accommodate special conditions. These flags are pinch and short. Pinch is used to identify that a geologic layer is not present (pinched out) for a particular boring. It is equivalent to using the value one column to the left. Short is used to identify that a boring did not extend to the bottom of a geologic layer. In the sample file below, boring C was not deep enough to reach to the bottom of the layer 3 or any subsequent layers. Rather than use the bottom of the boring (a meaningless number), the short flag is used so that this boring will not be used to determine the bottom of these layers.

File 1:

X	Y	TOP	BOT_1	BOT_2	BOT_3	BOT_4	BOT_5	BOT_6	NAME
Elev		Top	FILL	SH	SS	SD	SLS	GR	feet
11	7	1	1	2	3	4	5	6
5	3	3	-11.5	-22	pinch	-36	pinch	-59	A
13	5	3.5	-12	-22.5	pinch	-36.8	-37.5	short	B
24	7	5	-11	-24	pinch	-38.5	-43	-58.6	C
42	2	8	-3	-22	-23	-41.5	-46	short	D
57	11	7	-2	-13	-26.5	-42	-43.5	-63	E
72	14	7	-3	-8	-27.6	short	short	short	F
85	19	5.7	-5	pinch	-26.6	-38.3	pinch	-65	G
107	23	4.2	-5	-8	-26	-38	-41	short	H
123	35	2.2	-3	-13	-16.9	-37.5	-41	-66	I
136	24	3	-1.5	-15	pinch	-37	-37.5	short	J
145	18	4	0	-15.7	pinch	-36.3	pinch	-58	K

For file 2 line 2 of the file is Depth", therefore all surface descriptions for layer bottoms are entered as depths relative to the top surface elevations. This is a common means of collecting sample coordinates for borings. Note that the flags (pinch and short) are not affected by using depths versus elevations.

File 2:

X	Y	TOP	BOT_1	BOT_2	BOT_3	BOT_4	BOT_5	BOT_6	NAME
Depth		Top	FILL	SH	SS	SD	SLS	GR	feet
11	7	1	1	2	3	4	5	6
5	3	3	14.5	25	pinch	39	pinch	62	A
13	5	3.5	15.5	26	pinch	40.3	41	short	B
24	7	5	16	29	pinch	43.5	48	63.6	C
42	2	8	11	30	31	49.5	54	short	D
57	11	7	9	20	33.5	49	50.5	70	E
72	14	7	10	15	34.6	short	short	short	F
85	19	5.7	10.7	pinch	32.3	44	pinch	70.7	G
107	23	4.2	9.2	12.2	30.2	42.2	45.2	short	H
123	35	2.2	5.2	15.2	19.1	39.7	43.2	68.2	I
136	24	3	4.5	18	pinch	40	40.5	short	J
145	18	4	4	19.7	pinch	40.3	pinch	62	K

There is no numerical equivalent to using the short flag. It causes the kriging modules to select only those borings with valid data for computing the surfaces of each layer.