This looks like a dike, but close inspection shows that the rock is sandstone. Yes, that's exactly what it's called. This one is north of Lake Huron in Ontario. Clastic dikes form when sediment is partially consolidated but under high pressure. If a water-laden layer can find a weak spot in the overlying layers, it squirts upward.
Earthquakes are a common trigger.
Note how large pieces concentrated in the center where flow was fastest. The very uniform layers here are varves , alternating thick and thin layers formed in a glacial lake. The contorted zone running across the center is probably due to glacial ice shoving the upper layers of sediment over the lower layers. Soft-Sediment Deformation Submarine Landslides Submarine landslides are common on the edge of the continental shelf. The landslide flows scour flutes in the underlying sediment, then come to rest as graded beds of sand and silt that fill in the sculpted bottom.