21. Formed of striped gneiss, they are crisscrossed by an abundance of little diabase channels. 22. These created cracks which were later filled in with additional quantities of magma and diabase . 23. It may grow on amphibolite or diabase . 24. Devil Mountain is underlain by Nipissing diabase . 25. Typically this occurred where the olivine diabase unit dipped at right angles into a shallow drainage. 26. The iron content of the diabase is often identified as the source of the ringing ability. 27. Trap rock, i . e . basalt or diabase , has a variety of uses. 28. They are made from marble, a much softer stone and easier to process than diabase . 29. Like the other highest peaks of this area, Mount Ferguson is underlain by Nipissing diabase . 30. This geological process created large, thin, subvertical sheets of impermeable basalt, or diabase dikes.
