Spanish resort island to locals / MON 11-23-20 / Pink-flowering shrub / Horror film villain with knife / Locale of Oakland and Alameda

• DIDGERIDOO (18A: Australian wind instrument)
• MID-OCEAN RIDGE (38A: System of underwater mountains)
• BRIDESMAID (60A: Wedding attendant)

The parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus.

The parietal lobe integrates sensory information among various modalities, including spatial sense and navigation (proprioception), the main sensory receptive area for the sense of touch in the somatosensory cortex which is just posterior to the central sulcus in the postcentral gyrus, and the dorsal stream of the visual system. The major sensory inputs from the skin (touch, temperature, and pain receptors), relay through the thalamus to the parietal lobe.

Several areas of the parietal lobe are important in language processing. The somatosensory cortex can be illustrated as a distorted figure – the cortical homunculus (Latin: "little man") in which the body parts are rendered according to how much of the somatosensory cortex is devoted to them. The superior parietal lobule and inferior parietal lobule are the primary areas of body or spatial awareness. A lesion commonly in the right superior or inferior parietal lobule leads to hemineglect.

The name comes from the  parietal bone, which is named from the Latin paries-, meaning "wall". (wikipedia)

• The revealer clue is not accurate — There are not "two forms" of ID found in the theme answers. There is one form, found twice. There's just ID ... two times. Not, not, decidedly not "two forms." I get why the "forms of ... " phrasing is there, in terms of trying to evoke a common phrase related to IDs, but when your themers don't have "two forms," best not to say they do.
• What the heck is a MID-OCEAN RIDGE?— I have no doubt that it's a real thing, but that is not a thing that either Rachel or I had ever heard of. Seems kinda weird that you have to get that technical on a Monday, when the only theme restriction is 2xID. 
• Some of the fill is less than great— this is true esp. for YALEU, which, when you're solving Downs-only, is particularly gruesome ("What 5-letter answer ends -LEU?" A: nothing good). Lots of very common crosswordy stuff. Solid and inoffensive overall, though, for the most part, and the rather large / open corners kept the fill from being boring. 
• Neither of us knew PARIETAL — or, in my case, how to pronounce it :(
• There are so many ways this puzzle could've included more women and it just chose not to— CHRIS, DANA, PEARL, OSAKA, OBAMA ... lots of opportunities for cluing these answers as women. It seems like a low-stakes thing to many of you, I know, but just a little attention, a little thoughtfulness, even having the issue (of gender parity) on your radar, would go a long way. Please check out this visual essay from the website The Pudding ("Who's In The Crossword?"), which uses data gleaned from several major daily crosswords to illustrate the tendency of puzzles to underrepresent women and people of color.