. Bulletin of the Geological Society of America. Geology. BEGINNING 01? THE GORGE 37 control the Mississippi's course at that place. The buried valley is evi- dent at Mendota, opposite the mouth of the gorge, on the south side of the valley of the river Warren. An embayment lies in the valley's wall at Mendota. The back of the embayment is drift-covered or drift-filled, while the limestones and sandstone end abruptly on either side, as in case of a cross-cut buried valley. This buried valley may be a small branch from the buried pre-Glacial Minnesota lying south of Mendota, and it may have hea
. Bulletin of the Geological Society of America. Geology. BEGINNING 01? THE GORGE 37 control the Mississippi's course at that place. The buried valley is evi- dent at Mendota, opposite the mouth of the gorge, on the south side of the valley of the river Warren. An embayment lies in the valley's wall at Mendota. The back of the embayment is drift-covered or drift-filled, while the limestones and sandstone end abruptly on either side, as in case of a cross-cut buried valley. This buried valley may be a small branch from the buried pre-Glacial Minnesota lying south of Mendota, and it may have headed possibly a mile northwest of the present mouth of the gorge of the Mississippi. Such a valley transverse to the river Warren could have influenced that river's abandonment of the left channel and at the same time drawn the Mississippi into its present course. In cutting the deeper channel, as before described, the river Warren followed obviously the right side of its older high and wide valley (see figure 2). The abandonment of the channel on the left side of the island opposite Fort Snelling is accounted for in a general way as due to the drawing of the stream to the deeper channel as it was made. In partic- ular, however, one circumstance requires explanation, namely, the aban- doned left channel beds upon the limestone ledge, as low as the crest of Saint Anthony falls would be at any stage. From the upper end this channel appears to be a course of the Mississippi abandoned just prior to the recession of Saint Anthony falls. At the lower end there is no chan- nel nor alluvial beds and no evidence of a cataract where the Mississippi could have plunged from this channel into the deeper valley of the river Warren. The only explanation for that circumstance is that the river Warren for about a mile below the present Fort Snelling and the Missis- sippi for about a mile above that point may have settled in their valleys simultaneously and quickly as the oblique pre-Glacial vall
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