Page:The Journal of geology (IA journalofgeology21894univers).pdf/272
| 7. | Clay shales and sandstones, the latter sometimes white, all plant bearing,
much comminuted vegetable matter, matted beds of swamp plants, and well-preserved dicotyledonous leaves of Dakota types, determinable |
10 feet |
| 6. | Black clay full of carbonaceous matter, with locally six inches of impure coal | 4 feet |
| 5. | Quarry sandstone, massive, light pink, soft, weathering iron-brown | 60 feet |
| 4. | Soft yellowish and reddish sandstones | 100 feet |
| 3. | Drab-colored clays with carbonized vegetable matter and gypsum crystals,
interbedded with yellow sandstones |
30 feet |
| 2. | Soft yellow and reddish sandstones with some clay layers | 60 feet |
| Jurassic. | ||
|---|---|---|
| 1. | Olive gray, drab or bluish clays with reddish and yellowish sandstones, to
base |
|
This section may be represented diagrammatically as follows:
_(The_Journal_of_Geology_V2N3P258).png)
- Jurassic.
- Equivalent of plant bed in Section No. I.
- (Upper portion). Equivalent of cycad bed in Section No. I.
- Quarry sandstone.
- Dakota leaf bed.
- Fort Benton.
It will be seen by a comparison of these sections that they are in substantial agreement, although no effort was made to make them so. The crest of the divide in section I represents the Quarry sandstone of section II, which was probably considerably thicker at this point, fifteen feet more being found, exclusive of erosion, but these rocks were often much harder in section I, and no quartzitic rocks were seen in the quarry. On account of the debris thrown down from the quarry and other obstructions, it was not possible to examine the next member below with as much care as was desirable in view of the fact that it seems to be the equivalent of the cycad and fossil forest horizon of section