Laura McPhee's moments in time

Laura McPhee’s gorgeous, large-scale color photos are on view now in two exhibitions that are in many ways worlds apart: ‘‘River of No Return,’’ at the Museum of Fine Arts, features images of Idaho, while ‘‘Silent Steps,’’ at the Bernard Toale Gallery, is a smaller exhibit of Calcutta photographs.

All the photos share one thing, however: They depict time. They portray how the present collides with the past, the way a slap-happy toddler careens, blithely and heedlessly, into a grandparent ill prepared for the impact.

Inevitably, there is poignancy in the juxtaposition. In each case, the past has majesty, whether it is the landscape of the American West, our romantic projections onto that landscape, or the accrual of meaning in one Indian family’s home over centuries.

McPhee shoots her photographs the old-timey way, with a big viewfinder camera that takes in vistas and captures exquisite details. The results might make you weep with their sheer beauty — and because imbibing that kind of scope in one glance is akin to gazing up at the Milky Way and suddenly waking to your own minute vitality in the vast scale of the cosmos.

Speaking of scale, McPhee’s photos are giant, 8 feet by 6 feet. And ‘‘River of No Return’’ is an ample show, with 40 images mounted in the MFA’s Foster and Rabb galleries. That’s generous space alloted to a Boston artist. These pictures follow a tradition of American landscape art in which painters such as Frederic Church and photographers such as Timothy O’Sullivan sought to depict the grandeur of the land by writing it large.

McPhee’s lush version of the magnificent American landscape appears most benignly in two stunning images of the same scene, side by side, taken within weeks of each other. ‘‘Fourth of July Creek Ranch, Custer County, Idaho, June 21, 2003’’ features a rough-hewn fence covered with a frosting of snow as the sun glints off the white-capped mountains in the distance. The next picture, photographed that July 8, is all summer: wildflowers winking in the grass, the mountains lit gold by the long light of the season.

The light in McPhee’s work is palpable. ‘‘Campfire, H-Hook Ranch, Custer County, Idaho’’ shows deep blue shadows of people clustering around the red heat of a fire as night falls over the mountain in liquid blue veils. ‘‘Igloo Built From Downloaded Plans, Park Creek, Custer County, Idaho, March 2005’’ depicts the ice dome aglow, casting warm light over surrounding snow amid night’s deep dark.

In several photos, a rancher’s daughter, Mattie, embodies the collision between past and present. Mattie was in sixth grade when McPhee first arrived in Idaho in 2003. Both gangly and graceful, Mattie embodies a tension between free-spirited girl and adolescent trying to shape herself to society’s demands. Seeing Mattie in jeans, holding a speckled hen with hands that look as oversized as a puppy’s paws, and then seeing her in an eighth-grade graduation dress, as beguiling and mysterious as a young Audrey Hepburn, is bittersweet, as is the passage from childhood to adulthood.

Even McPhee’s most disturbing photos are weirdly beautiful. We see a skinned elk with the soft fur of its pelt beneath its carcass, which is largely covered in a taut subdermis, stark white against the red gore of the animal’s innards. ‘‘Winter Sampling to Study Growth and Diet of Endangered Snake River Sockeye Salmon, Pettit Lake, Blaine County, Idaho’’ sparkles, even as it is littered with shards of fish flesh; it recalls Winslow Homer’s glittering images of fish swimming and leaping in Catskill waterways.

There are no men, women, or children in McPhee’s Calcutta photos. In this city so crowded with people, it suffices to show their handiwork.

Most of these photographs depict the aging, sagging glamour of illustrious homes that have passed from generation to generation within extended families over 300-400 years. As with the landscape, there’s something enduring about these mansions. Here neglect, or perhaps poverty, has left its mark on magisterial house pride.

‘‘Colonnade of the Dalan at the BaghBazar, Bose House, North Kolkata’’ recalls ancient Greece: Pillars are scraped, scuffed, and crumbling, but the brush of warm sunlight across them whispers that they’re not past enchantment. Even more intimate spaces, such as ‘‘Puja Room in the Women Courtyard, Monmot Ghosh House, North Kolkata,’’ with its shrines placed before a worn-down wall, display signs of care in the face of decay.

McPhee takes the large view, and not simply through her viewfinder. She keeps her eye steady on the unnerving beauty of the vastness of time and space, and how each keeps on going, despite humanity’s endeavors, large or small.